A secondary mail server is one that can also receive email for one of the virtual servers managed by Virtualmin, but only as a temporary relay rather than the final destination. It is wise to setup a secondary server for heavily used mail domains, to act as a backup or holding place in case the primary mail server is down.

On this page, you can select other servers with Virtualmin installed to be used as secondary MX servers for new mail domains created on this system. Before any servers will appear, they must first be added to the Webmin Servers Index module, in which you must enter the root login and password for the remote server.

For each secondary mail server, you have the option of entering a different hostname to use in the DNS MX record, instead of the server's actual hostname, such as `secmx.yourdomain.com`. However, be sure that whatever you enter is a valid DNS name that resolves to the same server.

If the Save and apply button is clicked, any existing virtual servers for which email is enabled will be added to (or removed from) all selected secondary mail servers. In addition, DNS MX records will be added to (or removed from) their domains to refer to the mail servers.