Configure SmarterMail as a Backup MX Server

This article applies to recent versions of SmarterMail. View articles for SmarterMail 16.x and earlier

SmarterMail is powerful enough to be used as a complete mail system that performs multiple roles from a single server, including the role of backup MX server.

In the event that the primary mail server goes down, system administrators can set up SmarterMail to function as a backup MX server to ensure users continue to receive incoming email messages. When the primary mail server cannot be contacted, email servers will then attempt delivery to the backup MX server. When the primary server comes back online, the backup MX server will then deliver all held email to the primary server.

Before configuring SmarterMail as a backup MX server, you must ensure that the server is listening on the appropriate IP address(es):

1. Log in to SmarterMail as the system administrator.
2. Navigate to Settings>Bindings.
3. Click the IP Addresses tab to display a list of IPs that reside on the server.
4. Click each IP you want SmarterMail to listen on. A modal opens. On that modal, ensure all appropriate ports are enabled.
5. Navigate to Settings>Antispam>IP Bypasses.
6. Click Add, then add an entry for the IP address of your backup MX server. Be sure to save the changes.

Once completed, your primary SmarterMail server will perform IP based spam checks against the original sending server rather than the backup MX server. Next, follow these steps to configure SmarterMail as a backup MX server:

1. Log in to SmarterMail on the backup MX as a system administrator.
2. Navigate to Settings>Gateways/Failover>Incoming Gateways.
3. Click New, and select Backup MX in the Gateway Mode field.
4. Configure the additional fields here including the IP address of the backup MX and any spam settings. Save when complete.
5. Navigate to Settings>General and modify the Retry Intervals (on the Spool card) to the following:

10, 10, 10, 1440

6. Change the DNS Errors Before Bounce value to 5 and save the changes.
7. In DNS, add secondary MX records that point to the new server's IP address. Be sure to set the preference value higher than the main MX record.

All other configuration settings are optional. For more information about backup MX servers and how they work, refer to the SmarterMail Online Help. For information on using SmarterMail as a free gateway server, refer to the KB article Configure SmarterMail as a Free Gateway Server.


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For the last step (6) in configuring the primary mail server, there are two options: "Bypass Spam Checks" and "Bypass Greylisting". Should both of these options be checked?
Scott Jibben (11/23/2022 at 10:45 AM)
"Should" is rather subjective. If you're doing those checks on the backup MX server, you can probably disable them on the primary, not that it hurts to leave them.
Derek Curtis (11/28/2022 at 7:52 AM)