note 35096 added to ref.mail

I am using the mail function in php. It sends out emails ok, and I receive them ok when they are sent to accounts that are hosted. However when I send them to an account that is only a domain (i.e. the message is forwarded on to another domain) the message is never received. Any ideas as to why this should happen, and how I can resolve it? ---- Manual Page -- http://www.php.net/manual/en/ref.mail.php Edit Note -- http://master.php.net/manage/user-notes.php?action=edit+35096 Delete Note -- http://master.php.net/manage/user-notes.php?action=delete+35096&report=yes Reject Note -- http://master.php.net/manage/user-notes.php?action=reject+35096&report=yes