@vaporeon_ s/qmail, with s6-networking fur networking and TLS, all compiled from source and supurrvised by s6. the setup is your typical qmail install, if that means anything to you. dovecot fur IMAP, just installed from debian. certbot handles ACME; i manually installed it from pip in a virtual environment because the certbot-digitalocean-dns python package isn’t packaged by debian anymore