Stories
Slash Boxes
Comments
NOTE: use Perl; is on undef hiatus. You can read content, but you can't post it. More info will be forthcoming forthcomingly.

All the Perl that's Practical to Extract and Report

The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
 Full
 Abbreviated
 Hidden
More | Login | Reply
Loading... please wait.
  • Disclaimer: I do AV/Anti-spam for ~ 250,000 folk. Many of my e-mail addresses are also plastered all over the 'net, so I get plenty of these bounces too.

    Still, from my perspective, mail must *not* get lost. Failure to deliver a message to it's recipient must *always* generate a bounce message (i.e., an SMTP 5xx error).

    Why? Because I don't trust anti-virus software to always do the right thing. I don't trust anti-spam software to always do the right thing. I don't trust *BLs and local block lists to

    • I fail to see how an automated message saying "A message you didn't send to someone you don't know couldn't be delivered" is useful.

      • I fail to see how an automated message saying "A message you didn't send to someone you don't know couldn't be delivered" is useful.

        It's not. And if you've got an algorithm that can determine when to silently drop mail on the floor with no false positives, I'm all ears. But RFC 2821, s4.2.5 is quite clear on an MTA's responsibilities after it accepts a message. I don't think picking and choosing which bits of an RFC to implement is a good idea.

        Yes, 2821 is in need of an update to deal with today's In

        • If you can detect that the message contains a virus, don't send the virus back. If you can detect which virus the message contains, you can tell whether the virus spoofs e-mail addresses. If it does, don't even send a bounce.

          I gather from the fact that so many of these bounce messages say "Your message tested positive for Sobig" that both points are actually possible — and pratical.

          • If you can detect that the message contains a virus, don't send the virus back.

            Doesn't work if you're trying to save cycles for wanted mail, and rejecting messages based on attachment types, or other content (e.g., the presence of web bugs).

            To be specific, consider three sites, A, B, and C. B has the virus, and is sending mail to C, with forged headers that look like it came from A.

            If C refuses to accept the message (SMTP 5xx), it's B that generates the bounce message to A. The mail logs at B shoul

            • If C accepted the message and silently refused to deilver it then why would B retry? That makes no sense.

              As Schwern pointed out the anti-virus vendors do know which virus is which and they do know which ones spoof sender addresses so of course they shouldn't bounce those ones back to the 'sender'. They should simply say '200 Hmm Yummy' and do nothing more.

              But I have an even simpler rule ... Never generate a bounce response when a virus is detected. Any virus. Ever. By all means have your virus scan

              • Never generate a bounce response when a virus is detected. Any virus.

                As I say -- doesn't work if you're bouncing because of something else in the message (e.g., an attachment type that you don't want to see -- .exe, .pif, etc). This is much simpler to check for than doing a full virus scan, so it runs faster, so it's a better use of resources.

                By all means have your virus scanning software alert the recipient - as a human being, they can eyeball the sender address and decide whether they want to do anyt

                • Beware of talking cross purposes

                  PS: Railing against AV software that sends helpful notifications back (instead of a 5xx), is a completely different kettle of fish, of course. There's a special level of hell reserved for the authors of Norton AV, which is particularly offensive in this regard.

                  Agree. In the past 24 or so hours, I think I've had 185 "helpful" messages about viruses, versus 21 bounces. So it appears that both sides of this "argument" are right.

                  Personally I'd like

                  • Fuckwits who create AV software that sends me "helpful messages" for positively identified viruses that are known to forge headers to change career. (Yes. If you're reading this and you wrote one of those, however insulted you feel by me right now, you were doing something fuckwitted)
                  • all mail systems to 500 spam and other unacceptable content, rather than bounce it to the "envelope from". Given that most of this shit has faked envelope froms, once they drop their STMP connection it's the last you're going to see of the real sender. So only while that connection is still up can you co anything to send feedback to the true sender. (Although the feedback I'd like to send spammers isn't valid binary, given that 1 is only 5V)