Jason R. Mastaler wrote: > "Jesse D. Guardiani" <[EMAIL PROTECTED]> writes: > >> (again, a bounce, not an autoresponder, even though we're not sure >> how we'd identify that!) > > This is the problem. There isn't any way to reliably distinguish a > fatal bounce from an innocent auto-response given the huge variety of > auto-responders and MTAs out there. > > What you are looking for is a way to refuse mail from an address that > can't be replied to. This can only be done reliably in the MTA. > Refusing mail from bogus domains gets you part of the way there, but > not all the way because spammers often combine fake usernames with > valid domains. > > I just noticed that the most recent Postfix snapshot has a feature > that verifies a sender's existence (via reverse SMTP) before accepting > a message. This would get you what you want in a reliable manner.
How could it be implemented in the MTA though? The way I understand it (which may not be totally accurate) is that not all MTAs throw an error immediately if the recipient doesn't exist. qmail-smtpd, for instance, dumps messages directly to qmail-queue, which places messages in the outgoing queue. Then qmail-send calls qmail-lspawn for local addresses and qmail-rspawn for remote addresses. By the time qmail figures out that a user doesn't exist, the SMTP connection is long gone. (Or, at least, that's the way I think it works) Or are you saying that MTAs like qmail SHOULD verify users before terminating the SMTP connection in an ideal world, and that this functionality could then be implemented in the MTA? I'm probably flogging a dead horse at this point, but I still think it would be desirable to attempt to determine whether a bounce is an auto-responder or a bounce at the TMDA level. However, I'll shut my mouth about it in the future until I figure out exactly HOW I'd like to accomplish it. Thanks. -- Jesse Guardiani, Systems Administrator WingNET Internet Services, P.O. Box 2605 // Cleveland, TN 37320-2605 423-559-LINK (v) 423-559-5145 (f) http://www.wingnet.net We are actively looking for companies that do a lot of long distance faxing and want to cut their long distance bill by up to 50%. Contact [EMAIL PROTECTED] for more info. _________________________________________________ tmda-workers mailing list ([EMAIL PROTECTED]) http://tmda.net/lists/listinfo/tmda-workers
