If your primary has a tendency of going down an inconvenient times (like mine had), I highly recommend spending an hour (or three, if we’d include reading on th

If your primary has a tendency of going down an inconvenient times (like mine had), I highly recommend spending an hour (or three, if we’d include reading on the subject) setting up Dovecot replication with dsync. It’s pretty easy over a TCP connection (SSH for some reason didn’t work for me, so I’ve set up a Wireguard VPN between my hosts - also allows me to replicate KeyDB for Rspamd without having to set up a PKI for it), and works like a charm - backup MX receives mail if primary is down, and uses local Dovecot replica for delivery. When primary comes back online dsync makes sure they’re both consistent copies.