Not sure which mail notification you are talking about...could you maybe post one of the emails you are talking about? If not, the email form templates used are located in ../language/en/email as .txt files and you can edit the content as you wish.
Don't have a specific answer for this, but do have a further question around the Email Notificaions.
When our users 'Subscribe' to a Forum or to a topic, to be notifed via email when new information is submitted on the forum or topic, in the FIRST notification email they receive, is the statement "You can use the following link to view forum, no morenotifications will be sent until you visit the forum.".
Not the behavior we were wanting around this.
Modifying the forum_email.txt allows us to remove the statement, but how do we get the phpbb3 software to send notifications on ALL posts when they've subscribed to them, rather than forcing the user to view the notificaiton post message before they receive any more notifications?