@code{MAILHOST} environment variable.
@item :port
-The port number of the POP server. The default is @samp{pop3}.
+The port number of the POP server. This can be a number (eg,
+@samp{:port 1234}) or a string (eg, @samp{:port "pop3"}). If it is a
+string, it should be a service name as listed in @file{/etc/services} on
+Unix systems. The default is @samp{"pop3"}.
@item :user
The user name to give to the POP server. The default is the login