Originally Posted by falko
You can do it with a PHP header redirect:
header("Location: https://www.example.com:81/squirrelmail"); /* Redirect browser */
/* Make sure that code below does not get executed when we redirect. */
with the real directory.
You can also just setup a forward in the co-domains option to redirect mail.something.com to that site.
What I've been wondering is if there's a way to do this for all mail.*, so that all clients can go to mail.theirdomain.com and be redirected without having to manually set it.