Slashdot Mirror
Spam Catchers Block Latest Crypto-Gram
An anonymous reader writes "Bruce Schneier sent out a note about SpamAssassin and possibly other spam filters blocking his excellent Crypto-Gram newsletter. Fortunately you can get it here (early no less!)." Schneier's email reads, in part "Tomorrow I will be sending out the February CRYPTO-GRAM, as I do on the 15th of every month. In the process of creating this month's Crypto-Gram, I discovered that SpamAssassin thinks that this issue is spam, probably because of certain links and descriptions of scams in the text. I have anecdotal evidence that other spam filters block Crypto-Gram as well. ... I'd apologize for the inconvenience, but I'm not sure what I could do to make it less so -- I don't intend to alter my content to accommodate spam filters."
but why not distro the newsletter encrypted? then the spam filters wouldnt have anything to trigger the filters, and id say the target audience have the knowledge to unencrypt it when it gets there..
That's why most good spam blockers (especially OS X's Mail.app) use their filters but compare the senders to a whitelist so that your friends can send you whatever they want to. If you've been receiving CRYPTO-GRAM for a while, it should be on your whitelist, and the blocker should just let it by.
But you don't always want to get everything people send you (everybody has those people who send you things they think are funny but you just can't stand). So there should be levels of "friendship" in the whitelist, so that some senders can be considered dubious (their mail shouldn't be deleted like spam, but perhaps placed in a different "Uninteresting" folder).
Lack of eloquence does not denote lack of intelligence, though they often coincide.
False-Positives should be a non-issue. Either you choose to run a spam filtering software and live with thoose limitations or don't run a spam filtering program and deal with the extra emails about enlarging various organs that you will receieve every day.
I do tech support for a webhosting company and people call us every day complaining about their spam but as soon as we offer blocking software based on lists, etc all we get is complaints that some more-valuable-than-gold email is going to get lost and ruin their entire business.
This is a simple choice and people have to learn they can't have their cake and eat it too.
If religous zealots don't believe in Evolution, then why are they so worried about bird flu?
The first inclination one has would be to suggest that everyone close their open relays. But this depends on people doing the right thing all the time, and has proven ineffective.
Fortunately, there's another way.
Right now, everyone who receives mail has to listen to everyone who tries to connect. The problem is how do you separate the wheat from the chaff?
The solution is to take advantage of the information SMTP and TCP/IP give you when a connection is established. The fact that you're receiving a connection gives you the address of the sender. And during an SMTP transaction, one of the SMTP commands (the MAIL FROM command) gives you the domain of the email's sender, e.g. "MAIL FROM slashdot@sysexperts.com".
When you're sending email to someone else, you do so by looking up the MX records for their domain, which tells you which systems are responsible for receiving email for that domain. This gives us a possible answer to the spam problem.
Suppose instead of blindly accepting email from everyone, you were to take the domain given to you by the MAIL FROM command, look up the MXes for that domain, and reject the email connection if the IP address of the sender doesn't match one of the domain's MXes?
Now, suddenly, you would end up rejecting email sent from every unauthorized relay, because the owner of the domain can make any system that is allowed to send email on behalf of his domain into an MX (and, if he doesn't want that system to be used for delivering email, then he simply makes such systems the lowest priority MXes in the list and blocks outside port 25 connections to them ... something he's probably doing anyway).
Suddenly, the only systems that spammers can send email from are systems that they legitimately control and that are defined as MXes for a domain they control. Suddenly, spammers have to set up and maintain their own domains and their own boxes. The costs have just become a lot higher, which will get rid of most of the spammers.
And suddenly, blocking spam becomes orders of magnitude easier -- you only have to deal with spammers who have decided to pay the (now much higher) price for sending spam and who cannot use someone else's system to do their dirty work without permission.
Use 'slashdot stuff' in the subject line in any email you send me if you want to get past the spam filter.