``DOMAIN`` is the main mail domain. Aka, server identification for outgoing mail. DMARC reports point to ``POSTMASTER`` @ ``DOMAIN``.
These are really the only things it is used for. You don't need a cert for ``DOMAIN``, as it is a mail domain only and not used as host in any sense.
However, it is usual that ``DOMAIN`` gets setup as one of the many mail domains. None of the mail domains ever need a certificate.
TLS certificates work on host connection level only.
``HOSTNAMES`` however, can be used to connect to the server. All host names supplied in this variable will need a certificate. When ``TLS_FLAVOR=letsencrypt`` is set,
a certificate is requested automatically for all those domains.
So when you have something like this:
..code-block:: bash
DOMAIN=example.com
POSTMASTER=me
HOSTNAMES=mail.example.com,mail.foo.com,bar.com
TLS_FLAVOR=letsencrypt
- You'll end up with a DMARC address to ``me@example.com``.
- Server identifies itself as the SMTP server of ``@example.com`` when sending mail. Make sure your reverse DNS hostname is part of that domain!
- Your server will have certificates for the 3 hostnames. You will need to create ``A`` and ``AAAA`` records for those names,
pointing to the IP addresses of your server.
- The admin interface generates ``MX`` and ``SPF`` examples which point to the first entry of ``HOSTNAMES`` but these are only examples.
You can modify them to use any other ``HOSTNAMES`` entry.
You're mail service will be reachable for IMAP, POP3, SMTP and Webmail at the addresses:
- mail.example.com
- mail.foo.com
- bar.com
..note::
In this case ``example.com`` is not reachable as a host and will not have a certificate.
It can be used as a mail domain if MX is setup to point to one of the ``HOSTNAMES``. However, it is possible to include ``example.com`` in ``HOSTNAMES``.
*Issue reference:*`742`_, `747`_.
How does Mailu scale up?
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@ -154,6 +199,8 @@ correct syntax. The following file names will be taken as override configuration
Tim Möhlmann
6 years ago