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Replacing SMTP?
dousette asks: "In reading over one of the RFC's governing the SMTP protocol, and other RFC's as well, it's interesting to note that you see some big names and big companies from time to time. With all the loopholes in the current SMTP specification, is it possible for the Slashdot collective to come up with another one? Would it stand a chance in making it into a standard, or do they just listen to Cisco, AT&T, etc? I realize that a lot of people have a lot of ideas how things should be done (and they haven't been shy about posting them to Slashdot), but has anyone tried to write the RFC for a replacement protocol? As a side note (where I won't be shy about posting how things should be done), if there were a replacement trusted protocol, one could have mail received via that protocol bypass spam filtering, id checking, or whatever checks might be in place (saving processor cycles, etc). The regular checks could still be done on other mail received via the 'older' SMTP protocol. If more and more ISP's make use of this, SMTP could be gradually phased out... or if you are one for a sudden cut-over, just cut to the new one at the same time as the IPv6 upgrade!"
"is it possible for the Slashdot collective to come up with another one?"
SlashDot Transfer Protocol - Essentially, the way it works, is the information is posted on one single, easily crashed server. Then, this information is linked to by Slashdot. Then, said server is taken down. However, 1,000 other posters will have mirrored it by then, therby helping in the "transfer" of the information.
Jason Lotito
I suppose you've never heard of mod_gzip before, then?
SMTP is so deep-rooted and pervasive already it will be a long, hard change to implement. Every little cellphone that comes with a mail-client. Every router that has smtp alerting. Every application that uses it for various tasks... they would all have to be updated!
Doesn't mean it shouldn't be done, but don't be fooled into thinking it's just a "propose a new spec, step 2?, profit" type of deal....
--D
I'd like to simply see SMTP updated to require work. On establishing a connection, a recipient should be able to give the sender a task to complete that takes a second or two. The recipient will only accept the mail once the work unit has been done.
This would make it too slow to send spam, by making it simply too processor intensive. Legitimate users would be unaffected.
I agree, any solution to spam that relies on replacing the SMTP protocol is bound to fail for this reason. The current issues with IPv6 migration should prove to everyone that the strategy of rip-out and replace does not work. I think what needs to be explored are added backwards-compatitable extensions to the protocol. Perhaps adding a few commands for whereby some sort of public key exchange is involved.
The QWERTY-slow typewriter story has been debunked. QWERTY forever!
To me a big problem with SMTP is that is never authenticated. There's no way you can verify anyone actually sent you an email, short of PGP keys.
At least if some one had to authenticate to send as joe@bar.com, some spammer would have to hack your password before they used your email address as the "From:" in a mailing...which just happened to me.
Like IPv6? You mean most things will already be there but no one will support it, no one will care apart from a few and no one will implement regardless of how hopeless and disastrous the current implementation is?
Ah yes, like IPv6 indeed. You know, I'll send a shiny mail delivered by SMTP2* over an IPv6* internet about the release of Duke Nukem Forever* to my gaming-addicted girlfriend* on the day SCO coughs up some evidence*
Note:
* = May or may not require divine intervention.
Hate me!
Hrm, never seen that before, im2000 has some good idea for simplifiying things, but it seems like it would just be unreliable and unfeasible.
With the current system, an smtp server can go down, and no one would notice because no one was received their email yet, but with im2000, if the sending machine goes down, then no one can read their mail from there. This would create a lot of unknowns, "why can't I read my email?". Also what about people that don't have a full on connection, you don't want to require those people to be connected just to read their mail. Sure you can queue it for downloading offline somehow, but that's going to be much slower than normal because you have to connect to say 30 different servers where your email is hosted.
Also there's the case of somesmallcompany.com sending out a mailer/advertisement to millions of people, because the email is hosted on their machine, their connection/server might become overwhelmed, causing heaches for everyone wanting to read their mail. "Why does my mail load so slow?"
It's a nice try, but it'll never work.
Another thing, what happens when the message is done being read? Is it deleted on the sender's machine? If so, then how will the user remember that they sent the email to check if it's been read. If not, when will the message get deleted? Obviously it can't stay there forever.
The great thing about the current system, is that you just send and forget. If it bounces, you get a new email message saying hey, something went wrong. But with im2000, if the message hasn't been read yet, WHY? Did the user just not check their mail yet? Is there connection/routing problem where they suddenly occurred after the hosting server sent the notification, etc.
> I wish people would stop inviting rate increases or new charges as an answer to spam. It's not the answer.
:)
:)
And the perfect example is regular junk snail mail. It costs them to send it, yet even in the Internet Age(tm), I still get a ton of it. Obviously that's NOT the answer, so "Don't Go There"(tm).
I think locking down SMTP servers and requiring verified & correct return addresses would go a long way toward curbing spam. Then when you disallow someone to send you mail, it could really work.
A combination of white lists/black lists, and Baysian filtering stops so close to 100% of spam that it's really silly for anyone to be bitching about spam these days. I don't GET any spam anymore - 0. Not 0.001%, 0 - the integer 0, as in none. If I ever get another piece of spam, then I'll change my email address (I can do that more easily than most as I have my own domain.), though this isn't the answer for everyone - lots of people have e-mail addresses printed up on lots of expensive cards & letterhead, etc. For them, the white list / black list / Baysian filtering solution should suffice way more than anyone should practically need.
Stop yer bitchin', people, and implement the technologies that are already out there and work great. Plus use yer freakin' brains for a change, and don't spew out your real e-mail address to everybody who asks for it. Use your friend's!
Working out the details of an appropriate certificate policy is not trivial, though.
C'mon now; the IPv6 upgrade will be spread out over at least several decades. And both Microsoft systems and many US Government installations will still be using it a century from now, because it's "standard".
After all, it's now past the death of typewriters, and we're still using the typewriter keyboard from nearly two centuries ago. And we use a ridiculous rail gauge, because the standard was set centuries ago.
And here in the US, we're still using inches and feet, measurements based on the lengths of the thumb and foot of a long-dead king. And we call them "standard".
We will be stuck with IPv4 for long past the final download of anyone reading this.
SMTP will probably be around even longer. But that's OK; it's fun to impress friends by a "telnet 25", followed by typing in a message directly to the server. I like to use "MAIL From: dubya@whitehouse.gov", and ask them if they'd be interested in a nice job in the TIA program. Then I challenge them to prove from the message they get who actually sent it.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
Actually, I've been working on a broader based piece of infrastructure than a new mail protocol, but the first problem I intend to attack is mail.
RFC 822 is fine for messages, but the transport needs a big upgrade. Also, envelope senders and receivers are non-verifiable, and therefor broken. One day, spammers are going to start using mailing lists and message boards to construct a profile of people you talk to, and send you mail that appears to come from them, thereby making whitelists useless.
The basic premise of my general transport is that all messages are addressed to a public key and come from a public key. All messages are signed by their supposed source ID, and most messages are encrypted to the destination ID.
A public key ID plays a similar role to an IP address in an IP packet. There will be distributed databases that hold (signed) mappings between public key IDs and their locations using other networking mechanisms.
I'm trying to design this protocol and its implementation so its easy to encapsulate it in almost anything. My first connection to an outside protocol will be IMAP/SMTP.
It's far from being ready for even a public alpha yet, but I do have preliminary code for creating certain kinds of messages at https://svn.generalpresence.com:5131/repos/trunk/C ++/pract_crypto/. I'm borrowing heavily from Bruce Shcneier and Niels Ferguson's latest book, Practical Cryptography. The initial implementation is in a mix of Python and C++. It requires Swig and the GMP library. I haven't designed the implementation itself to be in the least robust against attacks by someone who has root on your machine.
I am calling the protocol 'CAKE' for now. CAKE stands for Key Addressed Crypto Encapsulation. It is a layered protocol, since I intend it to be layered on top of any other protocol you can think of. :-)
One intention of mine is to publish a hash collision problem along with information mapping a public key to a mailbox. First time senders will have to solve the hash collision problem to avoid having the mail thrown away. I'm planning on simply wrapping an RFC 822 message in a CAKE shell.
Need a Python, C++, Unix, Linux develop
Because the cost becomes built in to their business model. it won't stop, it will only hurt regular users to charge for email/services. Sure, their profits may be cut a little bit, but that's not going to stop them. if anything, they'll do it more, because if their profit margin is smaller, they'll have to spam harder... right?
Non-email messaging systems have been thinking about virtually the same problem quite a bit, and have come up with a set of solutions that try to solve what are fundamentally the same issues: message integrity, message non-repudiation, and message authentication. And the surprising part of this is that nobody really focused on the protocol, because it doesn't provide the path to a meaningful solution to the problem.
Case in point: web services. While initially the people who were playing iwth web services started out doing security at the transport level (i.e. with SSL and various derivatives thereof), but realized that something like WS-Security (where the security of a message is a part of the message itself) is the more optimal approach.
Why not just force the issue into the realm of S/MIME (and similar extensions to rfc822) and handle it at MUA space? You can cover virtually all the problems with SPAM by following the example of the reliable messaging systems and doing more with the contents of the message itself, rather than trying to say that messages have to transmit over a particular protocol. For example, depending on your trust environment, S/MIME signatures solve the authentication, non-repudiation, and integrity problems perfectly. What more do you need/want?
Maybe ISP's should charge users for each outbound SMTP connection they make? I'd happily pay 10 cents per email I sent if it would reduce the amount of SPAM I received. It would only cost me a couple of bucks a month too at the rate that I send email ...
John Dvorak suggested a scheme along these lines, and in theory, it's a good one, though I'd suggest a tenth of a cent, which would still make sending a million emails prohibitively expensive.
In practice, though, it's not workable. Spammers aren't using the SMTP server their ISP provides; they're using their own, just like most desktop Linux users are. As far as the ISP is concerned, Spammer X is making a bunch of outbound connections, but they're streaming out through the ISP's switches and routers, not through their SMTP server.
To impose a tax on certain kinds of TCP connections would require detailed inspection of outbound packets. This is because a single SMTP connection can involve the transfer of many messages. To be reliable, the ISP would have to parse every outbound packet bound for port 25 on a remote system in order to count the number of emails sent. I don't think most people want that level of attention paid to their private emails.
Moreover, this presumes that all ISPs participate honestly and thoroughly in such a system. All it would take is a few spam-friendly ISPs (and they exist, are legion, and jump around IP ranges like ferrets on a hot skillet) to render such a system useless.
The alternative would be to implement email billing at the recipient side. Maybe AOL and Earthlink can pull that kind of blockade off, but small companies and J. Random Luser cannot.
Bernstein's IM2000 proposal at least keeps the bandwidth consumption down, but that's primarily a cost issue for ISPs. (Don't try to convince me that if the amount of spam declined, ISPs would lower their prices.) The main hassle of spam for the user is that it takes time and energy to delete spam, and having to inspect the stuff with ambiguous could-be-from-someone-I-know subject lines would not be alleviated by IM2000; you'd still have to pick and choose what pending inbound email to read or delete.
The fundamental problem with email as a mail system is that it's open to anyone who wants to send mail -- which is part of the point of mail in the first place -- but there is no economic limiting factor for the sender as there is with paper mail. Since we can't eliminate the openness without destroying the utility of the system, the only possible strategy is to artificially impose a cost on the sender. Unfortunately, owing to the nature of public networking, the only remotely reliable way to do that would be to route all mail through a centralized clearing house. No one company will be able to establish such a monopoly, and I don't think anyone wants the alternative -- which is to have the government do it.
This may or may not be a soluble problem, but it is, as of today, still an unsolved problem. Personally, I think it's going to take national legislation and international agreements to stop it, and that will no doubt take a long time. Paper (actually clay tablet) mail existed for several millennia before the International Postal Union was finally established. Let's hope email is brought into line a little faster than that.
Proud member of the Weirdo-American community.
Well, I think those "loopholes" are all the zillions of features that people want, but they aren't good enough software designers to realize that the features belong in the layer above SMTP.
In particular, lack of authentication is a strength of SMTP, just as it is with IP. It means, for example, that I can implement my own authentication (or plug in PGP or whatever), and don't have to use the mail-transfer layer's after it turns out to have a serious hole that lets the spammers and con-men through.
Protocols that try to do everything for you have the inherent problem that, when a serious problem arises, you have to put up with it until the idiots at the vendor decide to solve it.
SMTP is simple enough that even a relatively incompetent programmer can do it correctly. You can type it yourself via a telnet connection.
And adding features in the higher layers is easy.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
Ever heard of it?
That's not the answer either. Microsoft, Yahoo, et al have been lobbying for this approach, and for good reason. They want to function as the certificate authority (CA). They want to determine who can or cannot send email. They can use that power to literally sell the ability to send spam. They can also use that ability to censor their opponents.
Microsoft also wants a new patented standard that can't be legally implement with open source software.
There is a key difference, in that IPv6 affects the hardware of every net-connected computer (not to mention router, hub, switch, etc) in the world (I believe), whereas changing the mail protocol should involve minimal hardware changes, but admittedly extensive software changes. It's easier and cheaper to change software than hardware.
As one of the posters in this thread pointed out, it would go a long way towards helping establish accountability on the part of spammers. If you have to be accessible in order for "recipients" of your mail to be able to read the mail, then I suppose you'd have to be pretty easy to track down and also sue under the current anti-spam laws.
... I've been using it on my server for years and really love it. I'd be particularly interested in hearing what your ideas are about the ways that we can solve the spam problem, given that you are the author of a complete modern mail system.
Anyway, it's just an idea. I think that the whole question of "should we come up with a new mail protocol" is kind of misguided because obviously the hard problems here are not technical, they're in dealing with the huge momentum built up around the current mail technologies. It seems to me that we already have all the technology that we need to solve this problem, it's more a matter of enforcement by ISPs. I was just posting the link because it was relevent.
If you're the same Mr. Sam that made Courier, then thanks
SMTP is not the problem. Open Mail Relays are the problem. As long as you can drop an SMTP box on the net and have it spew Spam to other mail servers you will have Spam. Any new Mail Transport Protocol will have to be backwards compatible. i.e., receive mail from old SMTP servers. You can't switch all machines over at one time, you need to roll out one box at a time and keep it all working all the time.
:-)
In the country where I live there is a general rule for farm animals, the farmer is not responsible for fencing them in, it is your job to fence them out. Mail is the same, its not my job to stop spam being sent, but to stop it being delivered (to my users) There are many ways to do this, a combination of a few can be very effective.
As for the home user, well stop buying into the "submit your e-mail and we will send you porn" forms on the sites you wife does not want you to look at.
I come to this discussion as an expert, albeit a bit dated, as I spent a number of years as the lone software developer supporting ALL email software at Apollo Computer (before it was bought by HP).
There once was a very interesting competing standard from OSI, the X.400 standard. Most people now think of X.400 as an interconnect standard for bridging the various email systems out there. Yet, it actually is a specification for a very robust email system in and of itself. It is based on a self-describing data representation... no, not XML since XML wasn't even a twinkle in someone's eye at that time, but ASN.1. That standard has been somewhat successful as used in X.500, which has become somewhat popular through its exposure via LDAP.
SMTP has never been a particularly strong standard. First, it is not the specification for a complete email system. It mearly describes a protocol for exchanging messages between two processes via the network. This is not sufficient to build an email system. Thus we also get POP and IMAP, and any number of supplimental bits that are not necessarily standards. Even sticking to exchanging email between two processes, SMTP has always been rather loosely specified. Sendmail has served as the reference implementation. Supporting sendmail was more a matter of figuring out what it was doing than reading the SMTP specification since sendmail used a far richer protocol for exchanging email than described in the specification. Thus, the question of what comprised a compliant implementation was more like (does it interoperate fully with sendmail) than going through a specification and checking off each element it described.
Apollo started a project to produce a native X.400 email system. It had a very rich set of features that go far beyond what we see today in Unix and Windows email systems. The project was put on hold when I was reassigned to a higher priority task, I was a member of a strategic technology team given the task of determining what "everyone" meant by the term "CASE Integration" with the goal of producing a corporate strategy and piloting and/or prototyping some initial products. Given the state of the CASE community, it sure seems like pursuing the email strategy would have had better long term success. Of course the CASE Integration project died a painful and horrible death when HP bought the company. Surely "SoftBench" did everything and more...
Check out RF2821.
There is a solution on the table and US law that requires the US government to use it. Its called X.400 and it is a mess. For a start you have to register your server and that used to cost something like $25,000 or maybe $40,000 for businesses. The Gossip program for gov email requires all email systems to migrate to this x.400 nonsense but I manged to get them to allow a migration path through SMTP (the others were worse and the only two that were even consididered that worked were SMTP and UUCP). The only encrytion addon for sendmail happens to be a result of work that started from encrypting x.400 stuff.
If you want to fire up your own X400 server to play with, grab isode and try to get it to compile on your machine without gagging if you can. Its one nasty bit of bad code.
SMTP isn't that broken. It works for about a billion people. Any attempt to "fix" it will break it for way too many of them.
After looking through the posts here (most of the +5 should be -5 Stupid), its clear that most of the experts don't understand email in the real world.
Encryption:
The 1st tings is email must be interceptable. Many governments won't allow high level encryption that isn't full of holes that allow them to play pack recorded streams. Most large email servers can't deal with the CPU load of full encryption anyway so 100% solid encryption is out.
Authentication:
Authenticating the server is very importaint to many sites. Once you start doing some level of encryption, you need to make sure you know who your connecting to.
Authenticating the client is the where spam issue comes from. There are many ways to do this but none of them are being done and none of them work 100% (which is why none of them work)
There is no way of knowing of a new business is a spamer or not. Therefore there is no way to filter out spamers that have enough cash to hook up to new ISPs all the time. (there are some stupid ideas like charging--my isp is rich enough, forcing all email out--my isp's mail server is up 100% doesn't understand MX,I can run my own server and it works so why chnage?)
reverse MX record checks only work if you can trust the ISP to get reverse dns working correctly and they won't deligate it to a spam house. The other choice is a verisgn like company to whitelist everyone or some sort of distributed whitelist (which the spamers will try to hack into)
As far as fixes:
The solution is patch sendmail, qmail, postfix, exim to understand email on port 26 (pointed to by a srv record) and if mail comes in on the new port, then it must be checked with a reverse MX record or its dropped. Get the clients to stop handing off email on port 25 (sendmail allows port 587 for that) Use something like the SSH transport layer to encrypt (i.e. set up the encrypted channel 1st and then figure out whos talking). Add a new smtp verify_message command so I can ask another server "did you send me messages Xcxczxczqweczx?". Patches for all 4 systems must come out at the same time but be tested aginst each other. The when an ISP figures enough of its mail comes in on something other than 25, kill port 25 forever. That will kill all the proxies and all the old email gateways that haven't been updated in years.
Or save up your money and buy your self an X.400 gateway license adn tell all your friends about your cool new email address with all thouse nice slashes and no @.
A combination of white lists/black lists, and Baysian filtering...
Stop yer bitchin', people, and implement the technologies that are already out there and work great.
This doesn't sound like a general solution for J. Random Homeowner.
It sounds alot like "Well, shoot! Quit yer bitchin' an just put in some tuned ports and performance cam! Hell, my grandmother could do that!"
My other car is a 1984 Nark Avenger.
I don't risk job loss (since I'm self-employed), but I do risk missed contracts. I use Bayesian. I've had an occasional false positive, mostly during the first couple months when I was building my corpus.
BUT: I'm currently receiving about 140 spams per day. Do you really think I'm going to do any better than Bayesian regarding false positives when I'm mass-deleting 140 messages? I think not. I'm almost positive I'm going to incorrectly delete more good messages than Bayesian's false positive rate when I'm dealing with such a huge number of emails manually.
Plus if your Bayesian system is half-decent you should be able to adjust its sensitivity. On mine 0-49% is almost always good email and 50%-99% is almost always spam. When I look for false positives I look for anything unusually low, such as 65% or so. If you want, just adjust your threshold to 65%. I've never had a valid email with a Bayesian score of, say, 90%.
> They either can't figure out the tools or don't think they should have to.
:-)
And this is the thing - they really _shouldn't_ have to. Bad UI really ticks me off.
> I agree, however, that people are generally naive/dumb when it comes to common sense issues like sending out email addresses at will or even worse...
The thing is - I intended that for this particular audience. _SLASHDOT_ users, of all people, should know by now how to avoid getting spam. I mean _really_.
> clicking on the "Remove" links from spam! VERY DUMB!
Actually, I've proven to myself this is a myth.
Here's my story:
Last year, around, say, September or October, I was getting, on average, about 200-250 pieces of spam PER DAY. This, I realized, just Would Not Do(tm).
So, since it was obvious I was going to have to shut down all my existing e-mail addresses, generate new ones, and be ultra-selective about giving them out in the future, I realized it was time to test that "Don't click on the remove me links" piece of advice. I'd given it out myself many times, even in an article I once wrote. Time to put it to the test! So, for the period of one month, I followed all the instructions on each piece of spam, every day, to see what would happen to my flow of spam. I kept track of who was sending me spam (the company/product/service, not the 'return address'). I found out that you WILL get LESS spam if you actually follow the advice in the spam, in general. My spam reception went from the 200-250 per day to around 20 per day, in the span of about a month. Obviously, this was still way too much frigging spam, but let me say this: the spam I kept getting was almost entirely from the sources that didn't have a (working) removal method, not from the ones that did. Many of the ones that did have an (apparently) working method DO indeed take a few weeks to start working. But, surprise of surprises, it CAN indeed lessen your spam, when it's offered and is working. Bizarre, I know, but I swear it's true.
I'd still rather make spam technically impossible than rely on that, though.
I propose TMTP - the Trusted Mail Transfer Protocol.
A combination of white lists/black lists, and Baysian filtering stops so close to 100% of spam that it's really silly for anyone to be bitching about spam these days. I don't GET any spam anymore - 0. Not 0.001%, 0 - the integer 0, as in none.
Have you done the power-curve analysis on that? My mother works at a law firm, and they once tried to install a spam filter. It was state-of-the-art, with Bayesian filtering, and white/black lists, and additional whitefilters on top. It blocked most (not all) of their spam. But it also blocked some tiny fraction of legitimate messages.
Even if you have the (extremely impressive) power curves of Paul Graham's Plan for Spam -- and that was on a very well-trained Bayesian filter written by a coding genious -- it is Not Good Enough when missing a legit email could get you sued for millions. Either you risk blocking legit email, or else you have to wade through a pile of spam bigger than that legit email... either way, another protocol would be nice.
I hereby place the above post in the public domain.