> Backup MX is a relic and a legacy. It breaks almost all spam filters. > Modern mail infrastructure doesn't need it, except in rare cases.
why so? I use one here at work with great success. I use Postfix so I'm no use to the OP. I don't have any problems with double bounces, and my spam tools aren't broken. I have noticed that spammers won't even bother trying to connect to the primary, they just try the backup thinking that my primary server will accept mail as a relay from the backup, which of course it will, but only if that message passes spamd, 3 rbls, and amavis/SA, in which case it would have passed on the primary one anyway if I didn't have a backup configured at all. Seems to be just fine. --Bryan
