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MIT Spam Conference Conclusions
RT Alec writes "The 2003 Spam Conference has concluded, reports InfoWorld. (related read: abstracts of the conference discussions). I was unable to attend the conference, but it appears all that was discussed was filters (client and server). I think the key problem is ISPs that do not block egress traffic on port 25. If you need to send mail through a different SMTP server than provided by your ISP, the admin of that server ought to provide you with a means of using it with authentication on a port other than 25 (you do have permission to use that SMTP server, don't you?). It is not too tough to set up an SMTP server to require authentication, or at a minimum to run off a different port. I am suprised that this is never mentioned as a cure for spam. If just AOL blocked port 25, this could reduce spam by 50% (I base this figure on close examination of the headers of the spam I receive). I was pleased to see that Barry Shein, president of The World (a Boston based ISP) was included in the talks. I am not sure by the abstract (see link above) posted if he mentioned blocking port 25. In a recent interview he did not mention it."
but what if people want to run their own mail servers? For their own domains?
Are you saying that if I want to run my own mail server, I should get in touch with the mail admins of every single mail server of everyone I might ever want to send an email too so that I can send it on another port?
That's ridiculous. I shouldn't need to subsidize MX providers.
Otoh, a good solution might be traffic shaping, or even a sort of intelligent traffic shaper that limits the number of actual emails per day.
Personally, I think SMTP is just obsolete. Schlepping anti-spam mesures onto it is like trying to put copy protection on CDs. It's just not going to work. What we need to do move to new protocols. Ideally two separate ones. one for personal mail, and one for commercial/bulk mail. The personal system would make it difficult to send out tons of mail, but easy to get into people's boxes, while the commercial system would make it hard to get into the box (i.e. you need to be pre-authorized) but, by definition, you could send out as much as you want.
Digital certificates and encryption would be helpfull, for one thing
autopr0n is like, down and stuff.
Please don't promote blocking port 25, whatever happens. That would be very annoying.
I'm already annoyed at being collatoral damage in the war against SPAM. I use mutt as my e-mail MUA, which is not an MTA and doesn't support use of an SMTP server. No problem; use sendmail or exim on my macine to actually *send* the mail. Except that I find out that some of my mail is bouncing, because my cable modem is in a blacklisted range (the range that includes "all cable modems"), and therefore being rejected by some SPAM filters. I don't run an open relay, I'm just using a program to send mail from my computer in the way that it is designed.
Very annoying.
So I have to configure my MTA to forward to a gateway SMTP server which won't be on the various RBL lists. A pain, but fine, I can do that. I've managed to get that set up... but I'm not using Comcast's SMTP server. Maybe I should, but after briefly using @Home's mail services, I've leanred simply not to trust the cable modem ISP services for anything. I've got web hosting outfits I pay for, so I can use those SMTP servers, configuring my exim to forward to them and use SMTP AUTH. But if Comcast starts blocking port 25, then *that* won't work, and I'll be stuck again. (And, of course, "getting another ISP" isn't an option, because where I live, the cable company's got a monopoly as far as broadband access goes. I *do* have another ISP I pay for for things like news and mail, on top of the cable modem. But, unlike where I used to live, I don't have the option of going with DSL and choosing the ISP to use with it.)
Let's please not put forward this idea. There's enough collatoral damage as it is. And it won't really cut back on the spam, either. It's very very fuzzy logic to assert that since 50% of the spam now comes from AOL customers, that shutting that down would cut spam by 50%. The spammers out there will just find other places to spam. Going after the spammers themselves, and not just some of the tools they use, is the only way to stop spamming. Anything else only temporarily inconveniences them, and meanwhile greatly inconveniences innocents.
-Rob
Does anyone have an idea how much spam comes through open relays vs. spam friendly ISPs?
It's now common knowledge in most academic circles that one can customize their email client to block spam via the utilization of a standard Bayesian filtering mechanism that keeps a document corpus of messages that have been marked as spam by the recipient of the emails. Any further emails received are then fed through the Bayesian filtering subroutine and marked as spam if they're tested as such.
.96. If you based the probabilities on word pairs, you'd end up with "special offers" and "valuable offers" having probabilities of .99 and, say, "approach offers" (as in "this approach offers") having a probability of .1 or less."
As Paul Graham writes, "A few simple rules will take a big bite out of your incoming spam. Merely looking for the word "click" will catch 79.7% of the emails in my spam corpus, with only 1.2% false positives.
One idea that I haven't tried yet is to filter based on word pairs, or even triples, rather than individual words. This should yield a much sharper estimate of the probability. For example, in my current database, the word "offers" has a probability of
Reply or e-mail; don't vaguely moderate. Ex-O'Reilly/MIT employee, now a full-time Google employee.
How many spammers use real addresses?
The problem is that they use an AOL connection to get online, then spoof through a korean SMTP sever.
I like the idea. But, also do it for most of the dial-up services. Cable and DSL does provide a way back to the spammer's home.
Fight Spammers!
Blocking port 25 is not the answer. It creates more problems than it solves. I am a senior sysadmin at a mid size hosting center, and we run mail services for a lot of our customers. The single biggest problem with mail is dealing with ISP's that block port 25.
Saying "oh, just run it on a different port" is not as simple as it sounds to us geeks. Sure, we offer SMTP on another port to get around those ISP's, but your typical nontechnical user doesn't even understand the problem, much less know how to apply the workaround. And during the time they can't send mail, they're blaming you. They're blaming your "broken" mail service, because the mailbox their ISP provided them with is working just fine.
So you set up the nonstandard port and tell them "point it here." Now you're wasting untold amounts of tech support time on the phone with the nontechnical users -- you have to figure out what operating system and e-mail client they're using, and hopefully it's a setup that someone in your tech support organization is familiar with. Then you have to walk them through the process of setting up SMTP on a nonstandard port, and setting up authentication if necessary. During that time, you've spent enough tech support time to make that account unprofitable this month, and the spammers have found some other way to deliver their mail anyway.
Blocking egress on port 25 is not a good solution.
Tired of FB/Google censorship? Visit UNCENSORED!
No, the key problem is ISPs that don't disconnect spammers and charge them for violating the AUP, as well as ISPs that don't even have anti-spam AUP's. Open relays are next on the list. True, blocking outgoing port 25 traffic on the routers might eliminate a lot of spam (not a significant amount: in my experience the majority of spams I get are from various Asian countries, though configuring Postfix to reject connection attempts from a dozen or so subnets in China has cut down drastically), but then again, dropping every packet would solve the problem even more effectively, because:
As soon as an ISP blocks port 25, any spammers using that ISP will run their spammachines off of different ports. If an ISP requires SMTP AUTH connections to their mailservers, how long before spammers start relaying through their own ISP servers? Ultimately, blocking port 25 will have no measurable effect on spamming, because if the ISP provides a means around it for sending legitimate mail, it will be abused to send spam. All your proposed remedy will do is make life difficult for those who run legitimate mailservers.
While they started out with the bayesian algorithm described by Paul Graham they quickly discovered that the effectiveness of his algorithm tends to depend on the values of some quite sensitive tuning parameters and that diffrent people can get wildly differing degrees of success depending on their configuration and the types of spam/ham that they receive. Gary Robinson wrote an interesting critique of Paul's algorithm and helped the spambayes team incorporate his so-called chi-squared combining scheme (which apparently isn't bayesian at all) which doesn't seem to depend so much on 'magic' numbers and their testing framework showed that it works surprisingly well for both small and large sets of messages.
It's still under active development although most of the ongoing work is centered around the user interface components (POP proxies, Outlook plugins, etc...) whereas the actual spam classifier hasn't changed much in a while.
Well worth looking into if you're getting too much spam. Who isn't?
Theo deRaadt of OpenBSD fame has put together a nasty little spamd, a daemon that attempts to tie up a spammer's resources. Basically, it slows down connection attempts and then sends a temporary error code back, sticking the spam in the mailqueue and letting the spammer try again, and again, and again. Designed to use up as few of your resources and as many of the spammer's as possible.
Excellent description of how to use it with your own self generated blacklist at http://www.benzedrine.cx/relaydb.html.
Unfortunately, it's only on OpenBSD so far. Can some one please port this to Linux by tomorrow?
This conclusion is simply and fundamentally WRONG.
It is critical for the future of the Internet that ISPs provide unmolested IP service. When ISPs are permitted to filter anything, for any reason, you start down a slippery slope. As soon as ISPs start trying to prophylactically control what goes on through filtering, they will find new things they need to control, for "security" or "liability" reasons. This will screw the end users by changing the 'net from its current state to a choice of which ISP's walled garden you want to be trapped in -- which ISP's filtering and censoring you want to pay for the privilege of being subjected to. It also screws the ISPs -- technologically it's expensive, it creates new problems for their customer service to deal with, draws the ire of some of their customers and civil liberties types, and the more they try to filter/control/censor, the more ISPs will be legally required to (the principle behind common carrier -- if I provide a neutral and blind service, I can be exempted from being required to control many things, but if I provide a controlled service where I can know what's going on, then I'm required to use my control and knowledge to prevent certain things or I can be held as aiding those things being done)
And it won't stop the bad guys. The worst thing about the spammers is that they're just smart enough that whenever any effective anti-spam measure comes around, they just find a way around it. Yes, AOL filtering outbound port 25 today will stop a lot of spam TODAY. And guess what? The spammers will just do something else. Open -- or cracked -- proxies are the up and coming new spammer tools. Please explain to me how cutting off outbound port 25 solves that problem. Please explain to me why spammers will just go away and stop spamming because you're blocking port 25 as opposed to finding some other way to spam.
This is a solution where the users lose because they lose functionality and are likely to lose more with it as precedent. It's a solution where the ISPs lose because they incur new costs and liabilities while only temporarily slowing down spam. It's a solution where the spammers lose least of all, they've been shut out of ISPs before and they've been blocked in various ways before and they already know how to do their deeds differently if they need to.
This is a really bad idea.
I am disturbed that a bunch of supposedly clueful folks came up with this.
Barry's proposal for that last point was a fundamental change in the economics of spam, as follows:
Basically, it boiled down to "Spam is currently in a gray area legally, so let's legitimize spam in order to divide the spammers into legal spammers (who pay handsomely for the privilege) and illegal spammers (who do hard time, just like people who cheat a utility company).
Challenging proposal, and great fun to hear him speak.
Send spam using AOL's e-mail client and your account is nearly-instant toast, thanks to automated rate-limiting software.
AOL set up rate limiting sometime around 07/98. Yes, it was THAT long ago. Note, as another poster has said, this wouldn't stop someone from using AOL as their ISP and connecting to another SMTP server for spamming purposes, but considering how slow (not to mention expensive) AOL-provided net access is, I doubt any real spammer would use it for even that.
Since most of the
---
DRM is like antifreeze, to the MPAA/RIAA it's sweet, to the consumers it's poison.
There are potential customers using AOL. A significant percentage of my existing client base either is using or have used AOL since before they became a client.
I really don't like the idea of ISPs blocking ports. That should be the responsibility of the end user.
Instead of blocking ports why don't they force users to sign an agreement that they won't send spam and if they do they'll pay each recipient $50/incident.
Then if a bonehead sends spam they can go after them and enforce their TOS. I believe AOL requires a valid credit card number to even do the free trials, but I'm just guessing.
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
It's interesting to see that the talks focused on heuristics exclusively. The main problem with all of these techniques is that they may classify legitimate email as spam as well.
...
Since two months, I've been using the Active Spam Killer (ASK) now, and this has been mostly successful. In short: If a person writes me an email, they will have to confirm the mail, unless they are on my whitelist or the email contains a magic key (which is included in my sig and will thus be included in a reply). Confirmation also places a person on the whitelist, automatically. Since most spammers forge the From: address, they are not able to confirm their mail, even if they wanted... -> Pretty much no spam (dropped from approx. 20-30 spam-messages per day to 1-3 per week). Sure, if you order a book at amazon, their computer might not confirm. Thus I look into the confirmation queue from time to time whether anything in there is legitimate. Thus far it has not yet occurred that a person would not confirm his/her email, by the way. ASK is well documented, written in python and easy to setup.
There is another similar system (which I haven't checked out): TMDA.
I am wondering why big corporations, universities, ISPs are not providing such a (preconfigured) system as an option in their email packages
As usual, nobody is reading the article, and hence everyone misses the real meat. Ignore the silly web-zine hack writers and just go here:
http://spamconference.org/
The talks are online.
I'm utterly confused as to why the other excellent response to this post has been marked "troll" twice.
First of all, CRM114 is just a language. Bayesian filters could just as easily be written in Perl or C. The language makes no discrimination whatsoever.
Secondly, the very point of Bayesian filtering is that it learns what you consider trash and what you consider treasure. You start with a training set of several hundred "legit" messages and several hundred spams, and it goes from there.
The reason it works so well on a person-by-person configuration is that certain phrases (eg, email addresses of people you know in the "From" header) correlate very strongly to good mail, while phrases like "click here" and "enlarge your" are almost certainly spam indicators. Everything between is personal; if you're on a BDSM list, your filter will learn that you like that stuff. Given a training set with your personal tastes, rates well in excess of 95% are possible.
Incidentally, this is why Bayesian methods aren't that great for site-wide filtering (that, and they would be tremendously slow); it's much harder to establish what a *group* of people considers to be "not spam."
Big deal if AOL blocks port 25. Then the spammer just uses an open proxy on port 1080, 8080 or others. I get scanned on those ports every week or two.
One line blog. I hear that they're called Twitters now.
I use e-mail autoforwarding to track spam. Every time I give my email address, I specify who I'm giving it to, ex. blah.com goes to blahcom@mydomain (anything@mydomain goes to the same hotmail box), so when I receive a spam, I can see which site sent it or sold the information, and block any e-mail coming from that site and everyone they sold it with To: line filters. Since most of the sites I wish to receive e-mail from are sites that don't spam me, this method has been successful in eliminating the vast majority of spam that I receive, down to only about 1 piece per day.
Your email provider delivers an email to you only if
it has a "Reply-To" field in the header AND
the Reply-To value has been accepted as a valid email address by another customer.
So in order for a person that just created an email address to email you, they would have to get their new address validated first and would receive a message to that effect the first time they tried to email you. They would have to get in touch with you or someone else under your email provider to get validated.
If you get some spam, you report it to your email provider and the ISP deals with the customer who validated the "Reply-To" address.
Email providers would set up peering relationships wherein they can share validated email addresses.
If the Reply-To value is faked, it would have to point to a validated email address and would probably bring severe damage to that email account. This method would push spammers into using this strategy, but it would certainly get them into more trouble that they currently get into.
I'm sure there are holes in my idea, so shoot away and educate me.
Rank comments and posts against each other at We-Rank.com
If you are using windows, and outlook, you can install SpamNet, made by Cloudmark.
I had to stop using Eudora, because I had so many filters (400+) to kill my spam that it took, literally, 5 minutes for my mail to appear in my inbox, which, needless to say was very frustrating and annoying.
Anyhow, I have been using Spamnet for about 7-8 months and, depending upon the time of day that I check my email it correctly blocked between 60% - 95% of my spam.
For example, since it is a peer based spam detection system, so the more users that vote that email from a particular sender is Spam, the more likely you will get it blocked. Eventually, it maps out and makes blacklists based on overall stats.
The point is, I took 2 days off for Xmas and when I checked my mail on the 27th, it filtered out about 295 of about 300 spam messages.
::.. check out some Cell Phone Reviews
- I think the key problem is ISPs that do not block egress traffic on port 25
And think a big part of the problem are the nuts who think filtering port 25 network wide is a viable option. Here are some real world numbers...Router #1:
30 second input rate 21782000 bits/sec, 6210 packets/sec
30 second output rate 12294000 bits/sec, 4651 packets/sec
Router #2:
30 second input rate 7543000 bits/sec, 2133 packets/sec
30 second output rate 12182000 bits/sec, 3183 packets/sec
(and that's business traffic at 0030ET Sunday -- it goes a lot higher during business hours.)
Routers have a lot of work to do already without having to look for spam. Devices along the lines of a Packeteer could be used to perform in-line packet inspection, but that'll get old real fast.
Yes, it's perfectly doable to filter dialup users either at the ppp line or the next hop router by either explicit blocks or redirection. Many ISPs already do this. (UUNet requires it, oddly enough.) But an equal many don't. Plus, there's a growing amount of broadband in the world.
Most companies buying network connectivity and hosting their own email systems expect them to have direct control over those systems and the routing of their email in both directions. It's a simple task to set a mail server to use a "smart host", but then one is at the mercy of those controlling that server(s).
Oh, and just how exactly will this stop them from sending spam? Exactly. Simply put, it won't. It just changes the origin of the spam and maybe speed up the response time for blocking it and dealing with the user. HOWEVER, it introduces a much larger annoyance: blacklisting of the ISP server(s) and thus hundreds or thousands of companies and/or users.
Next I suppose the ISP should be looking at the email to judge it's spamliness? Well, I'm gonna have to play my lawyer card on that bit of stupidity. The instant an ISP begins any type of content filtering, most of the protective provision of various laws cease to apply. In the eyes of the law, this would be exactly the same as the post office opening all of your mail to determine and discard what they feel is "junk mail".
In the end, spam is what it is because of the [censored] creatans who think they can make money by participating in any of a growing number of scams. Basically, technology cannot protect the internet from stupid people. (esp. when the standard was constructed in a "stupid people" void. I guess we've bred better idiots.)
""We conclude that spam sucks."
;-D"
Tax money well-spent
Hey now, those of us with 14" penises that make millions at home would disagree with that ruling.
The ISP does not block port 25 for traffic coming into their customer's systems, they block it for traffic coming out of them.
Their customers must relay their outgoing email through the ISP's mailservers.
Messages relayed by the ISP's mailservers can include header info that ensures that the originating customer can be determined. Then, if a complaint is sent to the ISP, they can decide which customer to deal with.
This only has to be done for customers that use dynamic IP addresses - when fixed IP addresses are used, that is adequate to identify which customer sent the message.
Of course, this will only be done by those ISPs that believe in being a good netizens.
There isn't enough spam.
Eventually, if spam is allowed to proliferate, we will all live in a world with lower APR on our credit cards, countless anonymous women in love with our cocks are that have grown 4" bigger guaranteed.
Enough of this conservative conspiracy.
On a serious note, I hate arbitrarily blocking ports. It won't do shit to stop spam, it's more about the ISPs wanting to block all the ports possible, to reduce the amount of traffic an end user can have.
I don't need no instructions to know how to rock!!!!
Do you have ssh access to your mail server? If so, just forward local traffic on port 25 through the tunnel to the remote machine.
ssh -L25:remotemachinename:25 remotemachinename
Works like a champ. I tunnel my IMAP and SMTP connections this way.
"Fighting the underpants gnomes since 1998!" "Bruce Schneier knows the state of schroedinger's cat"
In my opinion, this is a terrible idea, for a number of reasons. The first reason is the First Amendment of the U.S. Constitution. This would inhibit free speech by anyone who wants to send mail to anyone else.
Sorry, the First Amendment says CONGRESS shall pass no law... A private ISP can restrict your speech as much as they want when you use their service (within the bounds of contracts, etc).
Make it not profitable(or illegal). That's the simple solution
The illegality here would scare the pants off of all the spammers in Asia, I'm sure...
I pledge allegiance to the flag...
of the Corporate States of America...
Port 25 egress blocking is a good start to the spam problem for two reasons: First, it prevents a spammer from signing up and just doing direct-to-MX spam from that throwaway account. Not many spammers do this anymore, because its easily tracead and bigger ISPs kick those accounts fastest. Second, it limits a spammer's ability to abuse open proxies and relays on a network. Say clueless users are running a WinGate open proxy or an open sendmail relay on an older default Linux/BSD install on their cable or DSL line. A spammer could try to relay spam through it, but the egress block would stop it.
I see alot of complaints here about how such a block prevents you from running a mail server on your broadband line. People, this is residential service you are getting here. If you need to run your own mail server you need to find out about that when you sign up for service. A typical residential user never needs to connect to any SMTP relay except the ones the ISP provides. These users are also more likely to cluelessly leave their computers open to abuse. If you're responsible enough to run a mail server, and you really NEED one, get a real account.
Another option is to relay your mail over a non-standard port through a third-party email provider, if you really loathe your ISPs relays. This is my situation, and I use Lux Scientiae. They run a SMTP AUTH relay on a secondary non-standard port. It's locked down to prevent abuse, and SMTP AUTH lets them track down any of their users that abuse it. They don't accept incoming mail on that non-standard port, only relay for users, so it's not like they're re-defining SMTP to use a different port.
Of course, there will always be those ISPs that really don't care about preventing abuse. This is why blocklists even exist, to allow users to shut out the bad neighborhoods on the net. It would be nice if all those residential broadband users' computers couldn't be hijacked by spammers. As it stands, they are, so one way or another port 25 traffic is blocked.
Beer wants to be free
a) short messages don't get caught- no words that are going to be blocked, just a URL. The URL doesn't match because it's several words stuck together without spaces.
b) misspelt words don't get caught. If the spammer deliberately misspells the key words, then it goes through.
c) common words- if the spammer only uses common words, it is unlikely that the spam can get caught; the spammer can check all the words he uses for being common before he sends it.
d) pictures- if the spammer sends his advert in a GIF, the Naive Bayesian can do nothing.
Overall, I am pessimistic about whether filtering will work in the long run, but in the short run it works pretty good.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"I used to run a tiny ISP. What I did was *redirect* traffic outbound to port 25 to a local mail server. The mail would still be delivered, and that server was (obviously) set up to allow 3rd party relay from the correct set of addresses. I had a small customer base, but I never once had any complaints about this policy. The users could forge the From: header all they wanted, but the outgoing mail would always have a proper Received: header, at least.
As long as the mail server doesn't do anything more agregious to the mail than add a Received: header, I find it unlikely that any legitimate complaints could be made about this practice. It's certainly a much more gentle answer than simply blocking port 25 egress completely. At least this way it's more or less invisible to the end-user.
The problem with changing SMTP is that it's well-established and generally a good protocol. The problem with changing the default configuration for installation is it only affects new installations. Basically anything you propose which requires changes on the server, requires operators to agree. No strategy as such will work, unless operators are not given a choice, because their customers demand the upgrade.
I'd propose a slight change to SMTP servers so that they automatically block incoming mail from other servers that act as an open relay. It would not discriminate against open relays when sending mail, however.
What this does is effectively drops all users of open relays off the map. Once enough servers out there start doing this, all the open relays start getting fixed, because their users demand mail to stop bouncing. Open relay spam ceases to annoy everybody behind a protected server immediately, however, and you don't really care when or if those servers get fixed.
This isn't going to fix the general spam problem, where valid addresses are used for spam, but at least you can block domains that annoy you.
But the truth is, spam will never calm down until every unsolicited/untrusted message costs a nominal sum, which curteous people return in the form of a reply from valid messages.
Any connection between your reality and mine is purely coincidental.
Legislation is not the answer. We know how tech-savvy politicians are. Do laws stop corrupt CEOs from plundering corporate pensions or cooking the books? Do laws solve problems?
Terrorizing spammers is not the answer. Again, this is not solving the problem. Pestering less than intelligent people who exploit less than intelligent methods of mass communication does not solve the problem. It might be a thrill short term, but there are too many people who will spam if the current mail protocols persist.
So what is the problem? Strangers send me e-mail I don't want. What is the solution?
I won't pretend to be an expert. I'm not. However, I'm surprised better men and women have not come up with something, ANYTHING, to solve the spam problem. I am NOT suprised to see 90-100 unsolicited e-mails (from strangers) in my inbox every day. Somebody needs to come up with something. So here goes...
First, classify e-mail accounts. Home/personal accounts should be bulletproof. You only receive messages from people you have on your list of acceptable senders, your "inner circle." Shopping/e-commerce accounts: you can receive messages from merchants who register with some central agency/server. Business/work accounts: I dunno. Ideas? How should we handle mailing list type accounts? Second, every e-mail sent has something solid identifying it with a sender included. The identification is sent to the recipient. If the recipient has this identification in his list and it matches 100%, then the recipient fetches the message from the sender. So instead of the sender wielding the power, the potential recipient makes the call. Why allow just anybody to send an entire friggin' message to scores of people? Messages go no where until the recipient says so.
Finally, and this is where the law comes into play, if someone manages to fake out your list by saying he is someone he is not, sic the prosecutors on him. That's identity theft, pal. As it is now, e-mail headers are raw schitzophrenia.
So step one, classify e-mail accounts. Different classifications have different list of people you are willing to accept mail from. Step two, the sender sends his identification and maybe a subject header to the recipient. Step three, the recipient accepts the senders request and fetches the message himself, rejects it outright, or adds the sender to his list and fetches the message.
I don't know 90 people whose mugs I'd piss on if they set themselves on fire. Why should any of these rat bastards be able to dump a second or third bit in my inbox?
It IS a terrible idea; if you want to offer a public data service, then that's what you offer. You don't get to make exceptions just because you feel like it, unless you are declaring, in essence, that you are providing the service of selectively restricting traffic. And in that case, you become liable for every judgement you make about who to service and who not.
A bar/pub/saloon can restrict you all sorts of ways just because they feel like it. But this doesn't give anyone the right to stop you from getting drunk, trying to pick up strangers, or making a fool of yourself in public. A public communications service is different, and for a very good reason. bars and saloons are primarily there to provide a space for private associations; a communications infrastructure is there to provide a public infrastructure. and the internet points this out very well; it's public, accept the fact or build your own fucking internet.
It comes down to this; you are advancing the idea that the primary argument is "it's mine, i can do whatever i want with it". but in the interest of creating a just society (one where few people have an interest in destroying it), we recognize many "level playing field" exceptions to this. separate water fountains, "whites only" policies, etc. tell me who and what you are and i'll tell you how you depend on this fundamental fairness. i'll also point out that the internet isn't yours and if you can't play by its fundamental rules of openness then you have no business connecting to it.
Expanding a vast wasteland since 1996.
My guess is one day we'll see a web of trust used by our e-mail client to determine whether our e-mail gets delivered to our inbox or junk-mail folder.
Someone using a signature for spam would see himself removed from the web of trust, and those that verified the person as a non-spammer.
Just don't ask me how somebody that doesn't know anybody else with an e-mail account gets somebody else to vouch for him. (Maybe your ISP will vouch for you if you verify yourself with a CC or something?). Any thoughts?
Somewhat related is this approach I've been trialing quite successfully for the last month. I haven't been able to find any reference to anyone else doing this, and would welcome any comments. If it's a 'new site' (not dealt with regualrly and not seen recently) and it shows up clean on the variosu DNSBL's I use, then I send a temporary error code back. If they retur (after a suitable time delay - I use 15 minutes) and still come up clean, then I let it through. Advantages: * many spammers don't retry - ever (perhaps they get shut down, or someone closes their open relay, or they concentrate on more receptive targets) * those that do retry (often many hours later - average is 7.6 hours for spammers) are usually listed on the DNSBL's by then * I get to collect the list of mail addresses they are trying to send, and if they hit one of my spam traps (and there are many obvious dictionary attacks) then they immediately get marked bad even if they are not DNSBL'd * Doesn't waste bandwidth (or the hijacked resources of a open relay 'victim') which continually using a tar pit does Disadvantage * Genuine email from a new/infrequent source gets delayed 15 + (until their servers retry) minutes. Most geuine ISPs try at reasonable intervals - though some wait an hour. I'm willing to wait an hour for mail from someone new, who's not on my whitelist, given the amount of spam this simple technique filters. Obviously if everyone adopts this approach then spammers would deliberately work around it - but it would complicate matters for them - the time delay and reptetive nature of their attempts would make them even more obvious as spammers, and more easy to shut down. And they can't avoid the spam traps. Forgive me if this is obvious and well known - I'd appreciate any pointers to where this has been applied and any comments.
Recycle PCs and build a wireless community network www.hillsborough.org.nz
Short answer: Because you teach your filter what is spam. And everybody else teachers their personal filter.
So if your personal mail often has "penis" in it, the filter learns that it is not a good indicator for spam.
I use POPFile http://popfile.sourceforge.net/, and I have noticed that one of the best indicators seems to be certain server names.
Turning my notes for the day into something vaguely coherent, here are some hightlights from the proceedings. There are a couple of speakers that I didn't write anything down for, but from mid-morning on this should be pretty comprehensive. Apologies in advance if my notes lead me to attribute certain comments to the wrong speaker -- if anyone notices any mistakes please feel free to add corrections:
Bill Yerazunis - CRM114 & MailFilter
Because Perl "freaks him out", Yerazunis came up with the CRM114 minilanguage (points for anyone that gets the joke in the name without googling for it :), then wrote MailFilter in CRM114 as an implementation of a filter that can be used with Procmail or SpamAssassin or what have you. The basic idea is to decompose a message into a set of "features" composed of various permutations of single words, consecutive words, words appearing within a certain distance of one another, etc, such that the set of features N is very much bigger than the set of words X. You then analyze the features in various ways and if you get above a certain arbitrary threshold, you flag the message as spam & handle it accordingly.
He claimed that with this software he could get better than 99.9% accuracy in nailing spam, and a similar percentage in avoiding "ham" (the term everyone was using for false positives -- legit mail that was falsely identified as spam). One of Yerazunis' observations is that the best way to defeat the spam problem is to disrupt the economics: if a 99.9% or better filter rate were to become the norm, then the cost of delivering spam can be pushed higher than the cost of traditional mail and the problem will naturally go away without requiring legislation (which would be nice anyway, but we can't count on it).
The drawback of CRM114/MailFilter is that it can only handle about 20k of text per second, so it's not appropriate for large scale use yet. Still an interesting project to watch though: crm114.sourceforge.net
John Graham-Cumming - POPfile
Most of his very entertaining talk was about the ingenious tricks that spammers resort to to obfuscate spam against filters, including most diabolically one example that placed each column of monospace text in the message into an HTML column, so that the average HTML-capable mail client would render the message properly, but it would be absolute gibberish to most mail filters. The ultimate lesson was that any good filter has to focus not on "ascii-space" (the literal bytes as transmitted) but the "eye space" (the rendered text as seen by the user), which by extension may mean that any full scale spam parser/filter could also have to include a full-scale HTML & Javascript engine. Yikes!
As for Graham-Cumming's software, it's a Perl application, available for all platforms (Windows, Mac, & of course Linux) that allows users to filter POP3 mail. Interesting stuff if you're a POP user: popfile.sourceforge.net
John Draper - ShopIP
Most of Draper's work seemed to be focused on profiling spammers, as opposed to profiling spam itself, by throwing out a series of honeypot addresses & using data collected to hunt down spammers. spambayes.sourceforge.net
Paul Judge, CipherTrust
Judge's big argument, which no one really disagrees with, is that spam has become not just a nuisance, but an actual information security issue. To that end, he is advocating much more collaborative effort to address the problem than we have seen to date: conferences like this, mailing list discussions, better tools, and public data repositories of known spam [and ham]. To that last point, one of his observations (which others made as well) was that there are no universally agreed on standards for what qualifies as spam, so repositories for spam will not be accurate for all users (spam for your programmers will be the bread & butter of your marketing department, etc). Plus, there are obvious privacy issues in publishing your spam & ham for public scrutiny. And to add another wrinkle, one danger of public spam/ham databases is that spammers can poison them with false data, screwing things up for everyone. That said, he encouraged users to help out with building spamarchive.org.
Paul Graham
The man who organized the conference and kicked everything this week off with his landmark paper from last fall, A Plan for Spam. Graham's spam filtering technique famously makes use of Bayesian statistics, a technique popular with nearly all of the speakers. The nice thing about a statistical approach, as opposed to heuristics, simple phrase matching, RBLs, etc, is that they can be very robust & accurate; the down sides are that they have to be trained against a sufficiently large "corpus" of spam (most techniques have this property though) and they have to be continually retrained over time (again, this is common). Graham was too modest to produce numbers, but subjectively his results seemed to be even better than what Yerazunis gets with MailFilter, by an order of magnitude or more.
Like other speakers, he predicted that spammers are going to make their messages appear more & more like "normal" mail, so we're always going to have to be persistent about this -- as one example, he showed us an email he received IN ALL CAPS from a non-English speaker asking for programming help, and although it was legit, the filters insisted otherwise. "That message is the one that keeps me up at night."
Everyone interested in the spam issue should go read Graham's paper immediately.
Robert Rothe, eXpurgate
Rothe works for Eleven, an ASP company from Berlin selling a spam management service/application called eXpurgate. His talk was short on details about how the tool worked (mainly that it searches for bulk mail), focusing instead on the high level functionality it provides to users -- basically, they classify mail as safe, questionable, or dangerous, and let the users handle them accordingly. Another speaker that sees spam as a network security issue, so they built their system accordingly, with privacy of the client's mail content in mind etc.
Like many speakers, he warned about the dangers of an anti-spam "monoculture": that Bayesian techniques might be great, but if that's all anyone uses then spammers will catch on and adjust their messages to look more like normal mail, to the point that Bayesian filters won't work anymore. As a result, we're going to need to attack the problem from several angles, using different techniques, to keep the spammers off balance as much as possible.
Matt Sergeant, SpamAssassin
SA is a well known Perl application for heuristically profiling messages as spam, adding headers to the message saying for example "I am 72% sure this is spam because it has X Y Z", and passing off the message to procmail or whatever to be handled accordingly. SpamAssassin can handle a message throughput great enough that it can be deployed at the network level (whereas some of the others, which might have somewhat better hit rates, are still too inefficient at this point). Deployed this way, the differences in effectiveness for single vs. multiple users becomes very apparent, as 99% effective rates fall down into the 95-80% range. This happens because, again, different users define different things as spam, so mapping one fingerprint to all users can never work quite right. For an example of a tool that your company can deploy right now & get fast, decent results, SA looks like a good choice; but for the long run it looks like a Bayesian technique is going to get better performance, and SA is adding a statistical component to its toolkit. Good talk.
Barry Warsaw, Python Labs
This was another example of the "monocultures are dangerous" philosophy, as Warsaw explained how he is helping to use a variety of anti-spam techniques -- from clever Exim MTA configuration to good use of Spam Assassin & Procmail to fine tuning of the MailMan mailing list engine -- to work together to manage the spam problem for all things Python (Python.org, Zope, many mailing lists, a few employees, etc).
He pointed out that some very simple filters can be surprisingly effective: run a sanity check on the message's date; look for obviously forged headers; make sure the recipients are legit; scan for missing Message-Id headers; etc. In response to the person that originally posted the article, yes, he did mention blocking outgoing SMTP as an effective element of a many tiered spam management approach.
Among other tricks for getting the different filtering tiers to play nice together, they make heavy use of the X-Warning header so that if an alarm goes off in one tier of their mail architecture, other components can respond appropriately. Cited projects included ElSpy and SpamBayes.
Barry Shein, founder & CEO of The World -- or as he laughingly put it, "President of the World". Har har har
This talk was mostly a let down for me -- Shein has made his views very well known, and his ranting, rambling talk didn't really introduce any new ideas for anyone that had read that interview (some good jokes & quotes though).
His core argument is that spam is "the rise of organized crime on the internet", that filters are nice but that the mail architecture itself is fundamentally flawed, and that ISPs like his -- in 1989, The World was the world's first dialup ISP -- are being killed by the problem. Shein was very annoyed that all these talented people are having to clean up a mess like this when we should be out working on more interesting stuff, and not having to worry about this issue. His big hope seemed to be that legislation will someday come to the rescue, but he sounded very pessimisstic. (Others in the room seemed to feel that this was a very interesting machine learning problem, and weren't really fazed by his pessimism -- but then most of the people in the room don't run ISPs.)
He also suggested that we need to find a way to make spammers pay for the bandwidth they are consuming (rather than having users & ISPs shoulder the burden) but didn't seem to know how we might go about implementing this. At all.
Fun rant to cheer along to, but for me it wasn't very constructive in the end.
Jean-David Ruvini, eLabs SmartLook
This was an interesting product. Ruvini's company is developing an extension to Outlook 2000 & XP that will watch the way users categorize messages into folders, come up with a profile for what kinds of messages end up in which folders, and then try to offer similar categorization on an automatic basis. Think of it as Procmail for Outlook, without having to mess with (or even be aware of!) all the nasty recipies.
Obviously if you have a spam folder, then spam will be one of the categories it looks for, but more broadly it will try to categorize all your mail as you would ordinarily categorize it. This makes SmartLook a broader tool than "just" a spam manager.
SmartLook is another statistical filter, though it uses non-Bayesian algorithms to get results. eLabs' tests suggest that the product is able to properly categorize messages about 96% of the time, with no false positives, and (for their tests, mind you) that it performed better than Bayes filters over three months of usage.
One nice property of this tool was that it works well with different [human] languages -- some strategies fall apart &/or need retraining when you switch from English to some other language. For certain markets (eLabs seems to be a European company, perhaps French?) this is a crucial feature, and having a tool that works with one of the biggest mail clients out there (most people don't use Mutt or Pine, sadly enough) can be very valuable. Very clever -- watch for the inevitable embrace & extend three years from now.
Eric Raymond
He didn't say anything about guns, but he did try to correct one of the other speakers for misusing the term "hacker."
Like Graham, ESR is a Lisp fan, but he knows that the vast majority of people aren't, and he also knows that the vast majority of people need to be using something like Graham's spam software. So on a lark, he came up with a clean version in C, named it BogoFilter, and put it on Sourceforge, where a community sprung up to, well, embrace & extend it.
As good as Graham's Bayesian algorithm is, ESR felt -- as did many of the other speakers -- that the nature of your spam/ham corpus is much more significant than the relative difference among any handful of reasonably good algorithms. (Back to the often repeated point about how corpus effectiveness falls apart when used for a group of users, as opposed to individuals.) To that end, he strongly feels that the best way to deal with the spam problem is to get good tools into the hands of as many people as possible, and to make them as easy to use as possible (ahh, the old "open source UIs always suck" argument :). As an example, one of the first things he did was to patch the Mutt mail agent so that it had two delete keys: one for general deletion, one for "get rid of this because it's spam." That second key, and interface touches like it, seem like the way to get average people to start using filters on a regular basis.
Joshua Goodman, Microsoft Research
Unlike ESR, Goodman felt that algorithm selection does make a big difference, but this being Microsoft he refused to disclose what algorithms his team is working with -- except to say that, when delivered, they will be more accessible for average users than SpamAssassin, Procmail recipies, or Mutt :)
Microsoft has been working on the spam problem since 1997, but because of how big they are they've had unique problems in bringing solutions to market. As a case in point, they tried to introduce spam filters to a 1999 Outlook Express release, but were immediately sued by email greeting card company Blue Mountain because their messages were being inaccurately categorized as spam. With that in mind, they have been very reluctant to bring new anti-spam software out since then because they would like to see legislation protecting "good faith spam prevention efforts."
As a very large player, Microsoft faced certain difficulties in developing useful filters -- it may make sense for you as an individual to filter all mail from Korea, but this doesn't work so well if you are trying to attract customers *from* Korea :). This has forced them to put a lot of work into thoroughly testing different strategies before offering them to the public.
In spite of what millions of webmail users may have expected, Hotmail & MSN are currently being filtered by Brightmail's service, and plans are underway to reintroduce spam management features to client side software again. (Just imagine how bad it would be if they weren't paying someone to filter for them! Unfortunately, no hecklers piped up to ask if they are really selling Hotmail's user database to spammers, and if that is a source of annoyance for his team.)
An interesting barrier his group has had to grapple with was what he called the "Chinese menu" or "madlibs" spam generation strategy: that it's easy to come up with a template for spam -- "[a very special offer] [to make your penis bigger] [and please your special lady friend all night!" vs. "[an exclusive deal] [for genital enlargement] [that will boost your sex life!]" etc -- and have a small handful of options for each 'bucket' multiplying into a huge variety of individual messages that are easy for a human to group together but almost impossible for software to identify.
Michael Salib, extremely funny MIT student
Unlike nearly all other filter writers of the day, Salib's approach was heuristic: find a handful of reasonable spam discriminators, throw them all against his mail, and see how much he can identify that way. "It's sketchy, but this is a class project. I don't have to be realistic. [...] These results may be completely wrong."
Much to his surprise, he's trapping a lot of spam. He pulls in a little bit of RBL data ("the first two or three links from Google, whatever"), looks for some patterns and so on, and then churns it through LMMSE, an electrical engineering technique that as far as he can tell doesn't seem to be known in other fields. Basically this involves running the messages through a series of scary-but-fast-to-calculate linear equations). It turns out that he can process this much faster than a Bayes filter, to the point that customizing his approach for each user in a network would actually be feasible.
For a small spam corpus, he got results better than SpamAssassin did, though for a large corpus his results were worse; he couldn't really account for why this would be the case, or predict how things would scale as the corpus continued to grow.
When questioned about the RBL tactic by a member of the audience [who was apparently familiar to Salib -- I don't know who it was] about whether authenticating remote users might be the answer, Salib's response was "yes, I agree, but then you *do* work for Verisign, who is in the verification business, so you would say that."
Right on, Salib -- his talk was easily the funniest & breezy of the day :)
David Lewis, general researcher
The core of Lewis' argument, as ESR said earlier in the day, is that for any machine learning technique the quality of the learning corpus is much more important than the algorithm used. Bayes is one such algorithm, but there are many other good ones in the literature. In a dig at Goodman's refusal to disclose algorithms, Lewis pointed out that all of this has been publicly discussed since the first machine learning paper was published in 1961.
Observations: "lots of task inspecific stuff works badly, but task specific stuff helps a lot." It is important to use different corpuses [corpi?] for training and for general use, so that you don't train your machine to focus too much on certain types of input (this is a point that Microsoft's Goodman made as well).
As Graham did, Davis emphasized that spam is going to slowly start looking more like natural text, and we're going to have to deal with this as time goes on. www.daviddlewis.com/events/
Jon Praed, Internet Law Group
To a burst of tremendous applause, this talk began with the sentence "my name is Jon Praed, and I sue spammers."
He brought a legal take on the "not everything is spam to everybody" angle, emphasizing that we need a precise definition of what qualifies as Unsolicited Commercial Email (UCE). In particular, it has been difficult trying to pin down if the mail was really unsolicited, as this is where the spammers have the most wiggle room. However, if you can track down the spammer, they have to date rarely been able to verify that the user asked for mail, and so Praed has been able to successfully prosecute several spammers on this angle. He doesn't expect this to work forever though.
According to Praed, "laws against spam exist in every state, and more are pending", but he doubts that a legal solution will ever be completely effective as long as spam is lucrative. By analogy, he pointed out that people still rob banks and that has never been legal.
Praed informed the audience that there are several ways to get back at spammers, including injunctions, bankruptcy, and contempt, and all of these can be very effective. He pointed out that, to be blunt, a lot of these people are desperate low-lifes, and spam has been their biggest success in life. After these legal responses, their lives all get much worse. It hadn't occured to me to see spammers as pitiful before, but I can now. Most importantly, Praed stressed that these legal remedies can be very effective, and he strongly warned against taking vigilante action. This is almost always worse than the spam itself, and it only serves to get you in even deeper trouble than the spammer.
Identifying the sources of spam, most comes from offshore spam houses, abuse of free mail accounts (Hotmail & Yahoo, free signups at ISPs, etc) and bulk software (which may apparently soon become illegal in certain areas, provided that a law can be found to ban spam software while allowing things like MailMan or MajorDomo). Interestingly, he questioned the idea that header spoofing is a big problem, and claimed that in every case he has dealt with he has been able to track down the messages to a legit source sooner or later.
Suggestion: if you get a spam citing a trademarked product [e.g. Viagra], forward it to the trademark holder and they will almost always follow up on it. Suggestion: be fast in trying to track down spammers, as some of them have gotten in the habit of leaving sites up long enough for mail recipients to visit, but taking them down before investigators get a chance to take a look. Legal observation: spam is almost always fraud, and can be prosecuted accordingly.
Praed wrapped up his talk by citing the encouraging precedent that the famous Verizon Online vs. Ralsky case set: [a] that the court is interested in where the harm occurs, not where the person doing harm was when causing it (so if you send spam to someone in Alaska and spam is a capital offence in Alaska, you can be tried as a citizen of that state even if you caused the harm from somewhere else), and [b] it is assumed that you have to be familiar with a remote ISPs acceptable usage policies, and ignorance is no defence (just as you can't say "I didn't know it was illegal to shoot someone", Ralsky couldn't say that he didn't know Verizon prohibits spam -- (he had to have known that the AUP wouldn't allow what he was doing, so he deliberately didn't read it)). That precedent makes future prosecution of spammers much more encouraging. While, again, legal solutions may never eliminate the spam problem, a precendent like this can be an important supplement to filtering efforts (the stick to the filter's carrot, or something -- my lousy analogy, not Praed's).
David Berlind, ZDNet executive editor
His talk was primarily about how he receives a huge quantity of email from ZDNet readers, and he can't afford to use any spam filtering solution strategy that would allow *any* false positives. As one of the speakers said -- sorry, I forget who (Microsoft's Goodman?) -- getting a 0% false positive rate is easy: just classify nothing as spam. Getting a 100% hit rate is also easy: just classify everything as spam. Any solution besides those two is always going to have some degree of error either way, and determing how much of what kind of error you want to accept is up to you. Most users will tolerate a moderate false negative rate (some spam gets through) if it means that the false positive rate (legit mail is deleted) is very low. In Berlind's case, the false positive rate has to be vanishingly small, because reading all customer mail is a critical sign of respect for him.
Further, his business is also a legitimate mass emailer, sending out millions of free newsletters to users every day, and if Shein's proposal to bill bulk mailers were to catch on then even a very low rate would quickly put his company in the red. One obvious solution, which wasn't mentioned: start charging a subscription for these mailings, and make them profitable. I don't want to see this happen but if it did then the economics would tilt back toward making things feasible again.
Berlind is appreciative of the anti-spam work that is being done, but at the same time is skeptical of how pragmatic most of what is being proposed can really be. He feels we need a massive effort to rework the way mail is handled [Y2K anyone? It could get IT people back to work...], and to that end hopes ZDNet can help promote such a cooperative effort between the parties working on this. They don't want to be involved -- they are journalists & publishers, not standards developers -- but they are eager to get things going & want to cover the story as it progresses.
Like Shein said, he feels it's a waste for all these talented people to be working on combating penis enlargement offers, and hopes that we can find a way to get past this and work on real problems, "like world peace." This comment got a chuckle from the audience, but he seemed like the kind of guy that really meant that, and more importantly, he was right. A smart guy like Paul Graham or Bill Yerazunis shouldn't have to waste time tinkering with how many Viagra offers he can automagically delete when there are more fun things to be doing.
Ken Schneider, Brightmail
As mentioned earlier, Brightmail provides an ASP service for real time filtering of both incoming & outgoing mail. As would perhaps be expected, bigger ISPs and networks attract larger amounts of spam: 50% of mail coming into big ISPs and 40% coming into big companies is now spam. Brightmail offers the Probe Network, a <slashdot-killfile-term>patented</slashdot-killfil e-term> system of decoy honeypot addresses that gather data for analysis at their logistics center, which in turn distributes spam filtering rules to their clients where a plugin for $MTA (using the open source or proprietary MTA of the client's choice) can act on the database.
An interesting property of their system is that they have a mechanism for both aging out dormant rules as well as for reactivating retired ones, so that the currently active ruleset can be kept as lean & effient as possible. A big source of difficulty for them is legitimate commercial opt-in lists, because things have gotten more shady & blurry over time and it's now hard to tell this mail from much of the spam out there. Whitelists help here, but the problem is still difficult.
After each speaker had his turn, there was a panel discussion, but not much really happened there, and the moderator cut things short after only a couple of minutes. The original plan was for everyone to go out for Chinese food afterwards and continue the discussions over dinner, but when 580 people signed up that plan obviously fell apart. :) And so, here ends the notes...
DO NOT LEAVE IT IS NOT REAL
What is it with these story submitters and the inane comments they attach to the story? I seriously doubt "RT Alec" would have been a VIP guest at the conference if he feels port 25 blocking is the solution to spam.
I think the key problem is ISPs that do not block egress traffic on port 25.
No.. the ISPs that block port 25 already care about spam, they just block it to reduce their administrative load. It reduces the spam cases they have to deal with - but they still cut off spammers. If they didn't block 25, they'd still cut off the spammers. The actual problem is ISPs that don't care about spam. These ISPs don't deal with their spammers so how can you expect them to block port 25?
If just AOL blocked port 25, this could reduce spam by 50% (I base this figure on close examination of the headers of the spam I receive)
Funny, I base this statistic on the fact that you pulled it out of your ass. AOL has had spam problems, but they do deal with their spammers. It's ludicrous to suggest that they are responsible for half of all the spam on the Internet.
Tell me "RT Alec," how is port 25 blocking going to deal with rogue ISPs, who have a bulletproof connection through Verio? How about the clueless open relays that dot the maps of China, Brazil, and Argentina? What about for users of business DSL? Do we say, "you can't use your own corporate SMTP server, because you could be a spammer and we don't want to bother to deal with it?"
...and convince the Bush administration to blow up Shenjun China. That would eliminate about half the spam that I get.
> AOL set up rate limiting sometime around 07/98 [google.com]. Yes, it was THAT long ago.
And it made a big difference to the level of AOL origin spam.
> Note, as another poster has said, this wouldn't stop someone from using AOL as their ISP and connecting to another SMTP server for spamming purposes, but considering how slow (not to mention expensive) AOL-provided net access is, I doubt any real spammer would use it for even that.
AOL implemented transparent SMTP proxying during 1999-2000. They don't block outbound smtp entirely, but all outbound SMTP traffic is forced through their servers, is rate limited and is inspected for basic spamminess.
The admins can and would like to do more heavy duty filtering, but AOL legal won't let them.
AOL also rolled out their own DNSBL - ORBS style- but this was killed by AOL legal after open Earthlink customer relays smarthosting via Earthlink's main servers caused that ISP to be blocked.
Instead of fixing the fucking problem, Earthlink started screaming to the media about anticompetitive practices and threatening to sue.
Never min that AOL already won that battle - against Sanford Wallace in 1995 (Cyberpromo vs AOL - AOL was the defendant) - AOL legal forced the immediate shutdown of AOL's testing and blocking systems.
AOL admins would _like_ to do more about outbound spam. Their lawyers are a bunch of pussies and won't let them.
let's encourage ISP's to destroy accessibility to an essential service on the internet, in a misbegotten attempt to lessen illegitimate access. I don't want my connection censored! I enjoy having home broadband and running my own little server on it. My sendmail is set up to disable relaying, it's not like it's hard, and that is the true solution to spam. Spammers will always find a service that allows them the access they need, but this idiotic talk of blocking/censoring vital services/protocals doesn't help the rest of us.
BTW: Cause I run my own port 25 and have a static IP and a domain name, I get hardly any spam, personally. Why? Because I give out a different novel seperate address to everyone, and keep them all aliased to forward to my main account. If one becomes contaminated by spam, I simply delete it. If it actually was an address I gave to a correspondant [and not to some website, which is almost universally is] I only have to inform one person of a new address... come to think of it, that's only happened once...
---
the pen is mightier than the sword, the sword is mightier than the court, the court is mightier than the pen.
My notes on the conference can be found at http://commons.somewhere.com/buzz/2003/Technology. Notes.from.th.html. The really quick summary--everyone's got content-filtering fever, and I think they are nuts. You're trying to filter something that is NP-complete (Javascript email) and then do natural language understanding on it? I don't think so. Just as an example, consider the following three spams I've received recently.
Content filtering is doomed.
Oh yes, about blocking port 25. This is always followed by "and then your sysadmin can run SMTP on a different port so that you can connect to it via that." And if this becomes common, how long do you think until the spammers start scanning for alternate SMTP ports and doing direct delivery? In any case, it's moot. 90% of your spam isn't being sent from this country anyway. You're not going to persuade those remote sysadmins to block outbound port 25 any more than we've managed to get them to close their open relays. This is big business and big bucks.
so what happens when ipv6 finally gets rolled out to everyone and we all have static addresses?
In a nutshell,
- Lots of talk on Paul Graham's Bayesian approach and the derivative works that some people have been doing.
- Speakers were for the most part very inciteful, interesting, and funny (!)
- Some talk on the business side of things (Barry Shein)
- Some talk about exisiting "solutions". Our solution is the best (pretty boring. and nothing really interesting there).
Some stuff to remember and/or worth mentionning:
- When designing a spam blocker, use differrent corpuses of mail for developing, tweaking and testing. That will reflect better the real-world situation. (the only interesting thing the Microsoft guy said)
- The business of spam is more complex than it seems. It's about multi-layer marketing schemes and the spam itself is the product, not necessairly the Viagra or the penis enlarger
- Spammers are intelligent and getting clever to evade spam blocking software (one notable example of a mail written in monospace font, using HTML, and formattedd to write vertically, instead of left-to-right. The scanning software sees nothing recognisable!)
- The non-free e-mail subject did come up.
- You can always trace to the source. Maybe the sender is forged, but you can always go up the smtp relay chain. there will be a point where someone has an open relay (or it's the source itself)
- The MIT's infinite corridor is actually finite.
- Spam-control is really at its infancy, probably like anti-virus software was like in the mid 80s.
- Spam conference study have no need of penis enlargement, study says.
JP.
Please moderate this to that it can be seen.
--- Worst tagline ever.
You can debate the fine points of Port 25, SMTP and Bayesian filters all day, but unless you make the economics of spam less attractive, you will never get a handle on it through technical means. If you compare spam to physical junk mail, you'll find that it is a *lot* cheaper to contact (annoy) 30 Million folks by email, than it is by using printed letters or catalogs. Until that changes, the spam merchants will read the same technical posts that you do, and evolve their offense as readily as you evolve your defense. Until it costs actual money to send each email on the internet, there will be absolutely no incentive for spammers to ever stop what they are doing, and if there's even a small amount of money to be made, there is always someone deep enough in poverty or sleazy enough to do what it takes to make it. If you enjoy the technical challenge of fighting spam, then by all means have a really good time, but please don't delude yourself into believing that that there is anything going on here but traditional bottom line economics. Unfortunately, there is always someone low enough on the totem pole to be perfectly happy to step up and do those dirty jobs that only exist to annoy almost everyone else.
Art