diff --git a/mailserver.env b/mailserver.env
index b1496025..4c35fb9d 100644
--- a/mailserver.env
+++ b/mailserver.env
@@ -10,7 +10,10 @@
 # -----------------------------------------------
 
 # empty => uses the `hostname` command to get the mail server's canonical hostname
-# => Specify a fully-qualified domainname to serve mail for.  This is used for many of the config features so if you can't set your hostname (e.g. you're in a container platform that doesn't let you) specify it in this environment variable.
+# => Specify a fully-qualified domainname to serve mail for.  This is used for many of the config features so
+# if you can't set your hostname (e.g. you're in a container platform that doesn't let you) specify it in 
+# this environment variable.
+# **WARNING**: Setting OVERRIDE_HOSTNAME can have difficult to predict side effects.
 OVERRIDE_HOSTNAME=
 
 # REMOVED in version v11.0.0! Use LOG_LEVEL instead.