This may not make much sense to others but it’s all the things for setting up Exim4 in Debian that weren’t obvious.
- Add all the names and ip address to /etc/hosts
- Add ip address to exim4 files. Copy the other things added from the old server..
- Edit just the main folder after doing the exim4 dpkg
- Update /etc/letsencrypt to allow execute on /etc/letsencrypts/archive and live to get rid of the /var/log/exim4/mainlog pem related errors
- Remember the sasl stuff from Debian’s exim4 setup to let the user login.