Do you have a secondary MX? If so, we are happy to save you a few bucks today.

How? Well, here is some food for thought! Let’s see a few disadvantages of running a backup MX.

• It costs money. More often than not spam and virus protection will cost you extra for your secondary MX.
• They are spam magnets. Spammers love going straight to your secondary MX, even when primary is up. And when that happens…
• …you will backscatter. Secondary MXs are typically lame relays that happily swallow emails for non-existent recipients. When your primary MX refuses to accept the undeliverable email, the secondary MX will send an NDR to the original and obviously fake sender. At very least you will be NDR-bombing innocent people, or end up on backscatterer.org.
  Be a good netizen, do not backscatter.

Of course, secondary MXs have benefits as well, such us… well, nothing I can think of.

Backup MXs were invented to accept and queue email when your primary MX is down. So if you do not have a backup MX, you will lose email when the primary goes down, right? Well, not quite. Most modern MTAs will recognize your only MX is down and will queue the emails for a few days. What you really gain by a secondary MX is the ability to set your own queue timeout. If it takes a week to fix your primary MX, you surely can make good use of the redundancy.

Is it worth it? Only your situtation justifies it. If you do not find a reasonable excuse, though, drop your secondary MX. Or, buy another copy of ORF for the backup server. We love that option as well :)