Hey guys,
I found a great little tutorial from me back on the VestaCP forums in April 2016 regarding a Secondary MX (backup email server) server for VestaCP – it’s really easy to set up. Essentially what happens is when your main email server is offline or under stress, the third party email server (the one sending the email) sends the email to the secondary email server. Once that happens, the secondary email server attempts to send the email back to the first email server.
Read on for more information.