post...@corwyn.net wrote:
At 11:40 AM 5/19/2009, Noel Jones wrote:
Add an entry to /etc/postfix/relay_recipients:
@the.backed-up.domain.tld x
Technically correct, but unwise.
You must validate recipients for the backed-up domain.
why "must"?
Won't the mail just be forwarded to the primary mail server, who can
reject it there?
... which then causes your server to generate a bounce to the
(often forged) envelope sender. Your queue will be clogged
with undeliverable bounces, choking performance for legit mail.
Eventually you will deliver enough mail to forged senders that
your server will be blacklisted as an outscatter/backscatter
source.
...
maximal_queue_lifetime = 2d
That's quite short. Do you have lots of undeliverable mail?
For most of our mail, if it doesn't deliver in 2 days, it's never going
to deliver. And if it takes 2 days, it's already too late.
We often see people using a short queue lifetime to cover up
more serious problems with undeliverable mail. If you have
more than a handful of undeliverable mails, whether bounces or
not, you should address the problem more directly.
-- Noel Jones
