Would appreciate input regarding using multiple MX records for redundancy. There seems to be one school of thought that sees them as unnecessary - unless they are multiple primaries which the user can control. The theory being that if your primary server is down and without a backup MX , people sending you mail will receive a "delayed delivery" warning from their mailserver after 4-6 hours. Mail will be queued and delivered when your server is back online. Using a backup MX, these people will think that their email was delivered but you are still offline.