[Greylist-users] Broken MTA? - Exchange 2003 SMTP

[Matt Prigge]

Hi Folks,
    I apologize if this is a repeat of something that has been
discussed already. I went back through the archives several months and
didn't see any mention of the problem. I just implemented Greylisting
(using relaydelay) at a large corporation. It seemed to be quite
effective at first (even given some issues we had with an off-site
secondary relay that was pushing along quite a lot of spam). In
testing it a little, I noticed that a message sent from an Exchange
2003 server would immediately bounce the message if it recieved a 451
4.7.1 immediately after RCPT TO (error below). So, I experimented and
changed it to 4.7.0 (undefined security/policy), 4.3.2 (not accepting
messages), and 4.0.0 (undefined temporary failure) all of which caused
exchange to immediately bounce the message back to its user and *not*
reattempt delivery.
     Since Exchange 2003 is rapidly becoming popular, I wonder if
anyone has seen this and/or found a temporary error code that will
actually have that effect when issued to Exchange 2003.

- Matt Prigge


Error examples:

[With 451/4.0.0]
The following recipient(s) could not be reached: 

  test at greylisted.domain on 1/18/2005 1:29 PM
  The e-mail system was unable to deliver the message, but did not
report a specific reason. Check the address and try again. If it still
fails, contact your system administrator.
  <exchange2003.server #4.0.0 smtp;451 4.0.0 Please try again later (TEMPFAIL)>

[With 451/4.3.2]
The following recipient(s) could not be reached: 

  test at greylisted.domain on 1/18/2005 1:24 PM
  This message was rejected due to the current administrative policy
by the destination server. Please retry at a later time. If that
fails, contact your system administrator.
  <exchange2003.server #4.3.2 smtp;451 4.3.2 Please try again later (TEMPFAIL)>

[With 451/4.7.0]
The following recipient(s) could not be reached: 

  test at greylisted.domain on 1/18/2005 1:21 PM
  The recipient could not be processed because it would violate the
security policy in force
  <exchange2003.server #4.7.0 smtp;451 4.7.0 Please try again later (TEMPFAIL)>

[With 451/4.7.1]
The following recipient(s) could not be reached: 

  test at greylisted.domain on 1/18/2005 12:58 PM
  You do not have permission to send to this recipient. For
assistance, contact your system administrator.
  <exchange2003.server #4.7.1 smtp;451 4.7.1 Please try again later (TEMPFAIL)>