Getting fail2ban Working [with my weird choices] on Ubuntu 22.04 (jammy)

To put the tl;dr up front:

1. The systemd service name may not be correct
2. The service needs to be logging enough information for fail2ban to process
3. Unrelatedly, Apple Mail on iPhone is really bad at logging into Dovecot
4. Extended Research

[2024-04-26: Putting the backend in the DEFAULT section may not actually work on all distributions.  One may need to copy it into each individual jail (sshd, postfix, etc.) for it to take effect.]

A minimalist /etc/fail2ban/jail.local for a few services, based on mine:

[DEFAULT]
backend = systemd
[sshd]
enabled = true
journalmatch = _SYSTEMD_UNIT=ssh.service + _COMM=sshd
[postfix]
enabled = true
journalmatch = _SYSTEMD_UNIT=postfix@-.service
[pure-ftpd]
enabled = true
journalmatch = _SYSTEMD_UNIT=pure-ftpd.service

(The journalmatch for pure-ftpd removes the command/_COMM field entirely.)