Exim and backup relays

[Paul M]

Longman wrote:
> Ever since setting up a backup MX for my domain (via relay domains) I've
> started receiving lots of Frozen Message emails for Frozen Emails in the
> queue on this backup MX. It looks like spammers are using the the backup


what I've done in the past is to generate a list of valid recipients
from our zimbra mail server and push the file out to the backup MX so
that it always knows what's valid

we now use postini for A/V and A/S and there's an autoprovision feature,
 as well as a call-out-verification, but TBH we just manually provision
new valid recips in postini control panel as we don't make many changes;
when we upgrade to zimbra latest I'll probably invest more time.