mailto link to site admin contains webserver port

If you access Mailman's web interface via some other
port than 80, i.e. the port number is specified in the
URL and therefore in the Host header, it's also present
in the site admin mailto link.

Example:

If the Mailman URL is e.g.

    http://localhost:8001/mailman/listinfo

then the site admin mailto link reads

    mailman@localhost:8001

which isn't what it should be.

Fix: Strip the colon and port number before outputting
the host name for the email address.

Found in Mailman 2.1.3 on Linux using Postfix as MTA
(which probably should matter very much in this case ;-).

[http://sourceforge.net/tracker/index.php?func=detail&aid=856565&group_id=103&atid=100103]