Entry

Why does qmail fail abuse.net relay tests?

Feb 27th, 2004 04:57
Jonathan de Boyne Pollard, Dave Sill, http://homepages.tesco.net./~J.deBoynePollard/FGA/maps-relay-test-is-wrong.html

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%mail-abuse.org@myhost.mydomain
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 relaytest@mail-abuse.org and forward 
them.