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Why does qmail fail abuse.net relay tests?

Feb 24th, 2000 14:01

Dave Sill


Properly configured non-relaying qmail installations appear to fail some
simpleminded relay tests. These tests assume that if the SMTP server
doesn't reject MAIL/RCPT commands that could cause relaying in some
MTA's, that the tested MTA might relay them.
Because of qmail's modular architecture, it's not practical for the SMTP
daemon to validate recipients at the time of submission. These
potentially relaying recipient addresses will usually result in a
bounce--not a successful relay--when qmail-send tries to deliver the
message.
For example, qmail-smtpd will accept mail addressed to:
  relaytest%
But it will usually try to deliver the message to a local mailbox called
"relaytest%mail-abuse.org"--which will probably bounce. Some MTA's,
notably older versions of sendmail, would rewrite such addresses as
 and forward them.



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