configure HA mail server architecture using floating IP(s)
I have Postfix running on an Ubuntu 14.04 droplet which acts as a MTA for my domains.
I have spent a good deal of time hardening this config and implementing spamassassin, clamav, SPF checking, DKIM signing, etc. and am very happy with the setup I have right now.
I am looking for some guidance on how to proceed to the next step and add redundancy to my mail infrastructure by adding a second droplet and using a floating IP to allow failover in the event of either instance going offline.
Has anyone done this recently with Ubuntu/Postfix? My ultimate goal would be to have fully automatic failover with end users continuing to have full IMAP access to their mailboxes with no loss of emails.
Any/all comments, advice, guidance much appreciated!