Problem:

Does BackupMX have spam filtering?

Solution:

The answer to that question is both yes and no. Backup MX incorporates greylisting but not full spam protection. For full spam protection please see the section on profilter.

Unlike a FakeMX server which will reject the message with an SMTP 451 Error. Greylisting will tell a recipient to retry in 5 minutes, but only the first time the recipient is seen.

Most spam e-mail will try a server and if told to retry simple drops the message and moves on to the next victim. Whereas legitimate e-mail will try again and when Greylisting sees the address more than once it remembers the address so it only ever gets grey listed once.

BackupMX uses greylisting to help fight against spam and ensure the servers are doing what they are designed to best, which is service your legitimate emails and act as a SMTP Backup (SMTP Secondary) to your primary mail server.

Problem:

How do I use BackupMX?
How do I setup BackupMX?

Solution:

To use the Backup MX service you need to make a simple change to your DNS and add the BackupMX servers at a lower priority (thats a higher MX number) than your primary mail server/s.

Example 1

Lets assume your domain is called example.com and when you look up your MX records you get back something like the below

example.com   IN   MX   10   mx1.example.com.

When you sign up for the BackupMX service you will be allocated to a mail server. In this example the BackupMX server is called mx44999.smtp-engine.com.

All we need to do is add that server with a lower priority (higher MX value) to the list. So our MX list will now look like this

example.com   IN   MX   10   mx1.example.com.
example.com   IN   MX   20   mx44999.smtp-engine.com.

And thats it!! You're all done.

Problem:

What is Backup MX?

Solution:

Backup MX (also known as SMTP Backup or Secondary SMTP) is an email service that sits at a lower priority then your primary mail server.

Backup MX is essentially a SMTP Server that will accept email for your domain if your primary SMTP mail server fails or goes offline. 

When your server is offline the Backup MX SMTP server will accept the email and store it until the primary server (or alternative SMTP server) is back online and ready to accept emails again.  Then those emails on the Backup MX server will be delivered to the main server.

Problem:

What is Greylisting?

Solution:

Greylisting is a method of blocking significant amounts of spam at the mailserver level, but without resorting to heavyweight statistical analysis or other heuristical approaches.

Greylisting relies on the fact that most spam sources do not behave in the same way as legitimate mail systems. Although it is currently very effective by itself, it will perform best when it is used in conjunction with other forms of spam prevention such as profilter.