That's all fine, but then you're one hardware failure away from not being able to receive email.
I'm working on a guide on how to setup a replicated fault tolerant email cluster (galera/dsync) here [1] -- feedback appreciated.
This costs far more than something like fastmail, however. Depending on your situation you might value cost over peace of mind.
1: https://medium.com/@cyberpunk_networks/nsa-proof-your-email-...