Steve wrote:
Hi List,
What is the quickest, easiest (and scriptable) way to have Postfix defer
everything with a 4xx error. It's an extension to my 'after midnight'
tests. Not allowing any connections is fine, but I would prefer to
reject with a custom 4xx message such as "GO AWAY - IT'S AFTER MIDNIGHT
-- COME BACK IN THE MORNING"
It's an odd request to be able to 'offline' with a defer so I won't be
surprised if I can't do it, but I would be Cindy Ecstacy Ecstatic if I
could.
TIA.
Steve.
# /etc/postfix/deferall.regexp
/^/ DEFER Please try again during business hours
(this assumes you aren't using "smtpd_client_restrictions" in
your current main.cf. You can substitute any
smtpd_*_restrictions section you aren't currently using)
two commands to defer everyone with a custom message:
postconf -e
'smtpd_client_restrictions=regexp:/etc/postfix/deferall.regexp'
postfix reload
two commands to enable mail:
postconf -e 'smtpd_client_restrictions='
postfix reload
and you can skip the "postfix reload" if you don't mind "lazy"
implementation. Postfix will pick up the changes to
smtpd_client_restrictions as smtpd processes are replaced.
Some notes:
- this should be effective in stopping most "botnet" spam, but
no more so than greylisting.
- this will delay legit mail that arrives during the "after
hours" timeframe. The length of delay is controlled by the
sender, and could be significant.
- this won't have any effect on spammers that retry; it will
just delay their delivery along with the legit mail.
My recommendation is to just implement greylisting and skip
this nonsense.
-- Noel Jones
