Forked from T1113.
Step 2: domain preferences
We recommend for stability the use of mail.domain.tld, so if a domain is hosted elsewhere, there is a path not to have to migrate user configuration but keep the same.
That means for example to instruct to use "mail.wolfplex.be" instead of "mail.nasqueron.org" for @wolfplex.be addresses.
This asks to solve a certificate issue, as the value in hostname = the '''common name''' wanted by the mail user agent, and so deploy several of them to the mail server, per http://wiki.dovecot.org/SSL/DovecotConfiguration.
For SMTP:
- we can check if '''common name''' isn't a documentation error with a multi domain let's encrypt certificate covering mail
- if it doesn't work, another way could be to do the TLS terminaison in nginx, but that won't work for STARTTLS. In such case, we have to advertise to use TLS on submission port, and spawn a new submission server doesn't trying to do TLS, as nginx will do it.