@janusfox hehe failure siren! :3
But yeah, opensmtpd's my rec, it's WAY simpler and less annoying to set up than the likes of exim.
(If you're doing your own full-on mail server somewhere Dovecot is good for the IMAP side, as long as you chuck out all the config Debian ships with. All of it. Toss it in the garbage. You don't need it. They overcomplicated it to hell somehow, hah
but that doesn't matter for this, that's for wherever receives your "shit broke!!" emails. And is not a thing at all if you're sending it to an email account you already have.)
Anyway, if you install the opensmtpd debian package, it'll Provides: mail-transport-agent, automatically remove exim so you only have one, and everything will just use it (your system's mail server will provide a sendmail program that works with it and that's how stuff like cron or your own scripts can send mails)
opensmtpd's debian package USED to have a bug with TLS support which you had to install the one in backports to fix, but I thiiiink that was bookworm and not a concern now that trixie is the new normal.