There's no excuse for using IMAP or POP3 without TLS at this point. I thought
that port was an unambiguous "use TLS" indicator, but apparently I use the
imap/143 with ~STARTTLS (commit
8626ddaf5ec4 in adehnert-sysconfig/salt) with
Alpine, so seems good to enforce this on the server.
##
# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
-ssl = yes
+ssl = required
# PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
# dropping root privileges, so keep the key file unreadable by anyone but