Document that RELAYNETS is comma separated

docs/configuration.rst

@@ -73,14 +73,13 @@ The ``MESSAGE_RATELIMIT`` is the limit of messages a single user can send. This
 meant to fight outbound spam in case of compromised or malicious account on the
 server.
 
-The ``RELAYNETS`` are network addresses for which mail is relayed for free with
-no authentication required. This should be used with great care. If you want other
-Docker services' outbound mail to be relayed, you can set this to ``172.16.0.0/12``
-to include **all** Docker networks. The default is to leave this empty.
+The ``RELAYNETS`` (default: unset) is a comma delimited list of network addresses
+for which mail is relayed for, with no authentication required. This should be
+used with great care.
 
-The ``RELAYHOST`` is an optional address of a mail server relaying all outgoing
-mail in following format: ``[HOST]:PORT``.
-``RELAYUSER`` and ``RELAYPASSWORD`` can be used when authentication is needed.
+The ``RELAYHOST`` is an optional address of a mail server to use as a smarthost for
+all outgoing mail in following format: ``[HOST]:PORT``.
+``RELAYUSER`` and ``RELAYPASSWORD`` can be used when authentication is required.
 
 By default postfix uses "opportunistic TLS" for outbound mail. This can be changed
 by setting ``OUTBOUND_TLS_LEVEL`` to ``encrypt`` or ``secure``. This setting is

towncrier/newsfragments/360.bugfix

@@ -0,0 +1 @@
+RELAYNETS should be a comma separated list of networks