since the vast majority of members have no problem with email notifications for posts or pm messages, i'd say it's and issue on your end. possibly server or email based. since your mail is web based via google, it would need to be tested. you can test it yourself if you create another new email account, go to 'my profile' and change your email address to the new account, log back on with the new password yer given, post a reply to this thread and see if your notification works.
BUT for starters, you can forward me the notification email that trad gang sent you that went to the dead page.