You already did this once

You did not fail at this

You stopped being paid to do it. Running mail properly is a job — DKIM, blocklists, backups you have actually tested. Doing it for free, at night, forever, is the part that does not work.

Same software. Someone else’s Sunday

Nextcloud, Vaultwarden, Immich, a real mail server — the same things you chose, on hardware you own, under your domain. You keep the control. You lose the pager.

You are not locked in either

The registrar account stays in your name. You hold the backup key. If you want it back, you take it back — documented, standard formats, no export ticket.