Remote backup Postfix server


Remote backup Postfix server
\ Victor Trac (13 Mar 2008)
. \ Bastian Blank (13 Mar 2008)

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Subject:	Remote backup Postfix server
Group:	Postfix-users
From:	Victor Trac
Date:	13 Mar 2008

Hi all,
I have a postfix server running at one location handling email for a
number of domains. The domains all have A records that are part of a
single class C. I want to build another Postfix server at another
location as a backup, in case the first location loses connectivity.
What I envision is setting the backup server at a lower MX priority,
and if the primary ever goes down, the backup will queue mail until
the primary comes back up.

My problem is that I have a large number of domains with a large and
ever changing number of LDAP-backed users. I would like for the
backup server to only accept emails for domains that have A records
belonging to our class C. Is there a way to have the backup postfix,
perhaps by calling an external script, do a forward DNS lookup on the
incoming mail's host/domain portion and only accept the mail if it
belongs to our class C? I don't want to have to update the backup MX
server every time I add a domain or a user to the primary postfix box.

Or does anyone have a better idea as to how to provide backup mail
services without having to maintain an alias list on the backup
server?

Thanks,
Victor

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