Problem

What is FakeMX?

Solution

FakeMX (sometimes called, but shouldn't be confused with Fake SMTP) is an email service that sits at the lowest priority of servers for a domain and fights against the spammers.

Many SPAM mails are sent to the lowest priority mail server in the hope that you have less anti-spam systems in place to deal with the mails, others may randomly pick an MX server to send to.

Legitimate email is normally sent to the highest priority mail server that is online, if mail to this server fails then a lower priority server is tried.

Any email that tries the Fake MX server receives a SMTP 451 Temporary error and told to try again. At this point the majority of spam gives up and moves onto the next victim, whereas legitimate email will retry using a different mail server in the DNS MX list.

FakeMX is a great way to reduce the amount of spam emails hitting your primary and backup email servers.

Note, FakeMX isn't a spam filter, for that you would need profilter.  FakeMX is simply a server that tells all received email to come back and try again in a few minutes, because time is money to spammers they usually give up and move onto the next spamming target.  However legitimate email will try again using the primary email server for delivery.

FakeMX can often remove 40-60% of spam, leaving the spam filter on the primary and backup servers less loaded when to deal with the remaining spam and genuine emails.