Who Is Sending Welcome Message? M2P or BuddyPress?

When a new member registers they receive a welcome email. I'd like to change the content but can't find out where to do it, although I recognize the content that is currently there as mine.

Does the welcome message come via M2P or BuddyPress, and if I install BuddyPress Welcome plugin, will the member get two different messages?

Thank you.