Re: How to change email notifications
The code is located in wp-includes/wpmu-functions.php (it is a big file)
A few caveats:
1) There is text for the user signup email and for the blog signup email (blog signup email is also in the admin panel)
2) There is text for a bunch of other emails, alerts and notices. All over the place
3) The text is located in some squirrely locations, so move your cursor slowly (I missed some of the phrases a few times)
4) Keep a log of what you change, because wpmu-functions.php will change with WPMU upgrades.
5) You probably already know to avoid apostrophes and other symbols–depending on which ones you use, errors show up. I just avoided contractions.
Hope this helps.