Create a mail server secondary MX
Currently I have a server with email only 1 MX. Made through the tutorial: https://www.digitalocean.com/community/tutorials/how-to-install-iredmail-on-centos-6-5-x64
But at times, there is a server unavailability and would not take a second to go through the trouble.
Some companies have several lodging MX records, and would like to have more 1. Placing or to follow tutorial?