I had a topic similar to this a few weeks ago, but just did a bit more testing and hoping I can get some help. I am using ultimate facebook with buddypress 1.5.1 and multisite I am requiring registration with facebook, so users can only see the facebook registration page.
I have 2 scenarios...
1. they go to the facebook registration page and they are not logged into facebook. They fill in the information themselves and everything works great...they get a welcome email from the wordpress system that I customized.
2. they use facebook to auto fill the registration form. A user and a blog is created but there is no email sent to them.
Is the there any chance this is going to get added to the next release, or could you help guide me to adding it to my site?