SPAM a SMTP

This server is sending delayed bounces/challenge response mails/out of
office mails/other robotic mails in response to forged spam.  Some of
these bounces were received by our spamtraps.

Spamtraps are email addresses that do not exist and have never existed;
they do not send mail and they should never receive mail. Nearly all of
the viruses, worms, and other malware now in circulation forge the
"From:" addresses in spam. This generates bounce messages to email
addresses which did not actually send the email and had nothing to do
with the original email. This does not affect only Spamcop's spamtraps,
blocking lists, and reporters, but also normal users everywhere -- your
server is likely sending out large volumes of these bounces to innocent
bystanders.

Some suggestions:

1) If you need more evidence of this problem, please check your own
postmaster/mailer-daemon account for double-bounces.

2) If you are going to reject mail, do it DURING the SMTP conversation
with your mail gateway rather than after. Rejecting mail after accepting
it generates a delayed bounce generates a delayed bounce message

3) If you absolutely must send delayed bounces or other robotic replies,
do it from a "sacrificial lamb" IP, so that if it is listed in blocking
lists, the rest of your email will not be blocked.

4) Instead of sending bounces for invalid accounts, create a catch-all
account to accept mis-addressed mail.  Assign a human being to sort
through the mail and decide what to do with it.  It is likely you will
find the vast majority of the mail is not worth bouncing at all.  If you
find accounts you do want to bounce, then bounce mail for those accounts
at the gateway.

5) Make certain that the bounces you generate are RFC compliant and use
a null < > return-path.  See RFC2821 sections 3.7 and 4.5.5 for more
information.

6) If Majordomo replies with a "help" message in response to inbound
spam, these URLs may be useful:
http://www.casano.com/majordomo/
http://forum.ensim.com/showthread.php?t=15753