Hey I was wondering how you do this technically? Do you for example give Joe Smith a new email address (i.e. joe.smith@service.com)? Or do you change the name-addr for a no-reply@service.com?
Basecamp and GitHub set From: to something that looks like "Joe Smith" <foo-bar-123124312313@github.com>, which is enough to have GMail display the email as from a "Joe Smith" in the inbox.
We're just changing the from name for the email, and each notification has a unique email address associated with it, so it shouldn't trigger any scam warning.
Facebook sends email notifications about new messages with the sender's name in the From field, but uses an address like "notification+[randomid]@facebookmail.com". In Gmail, at least, the sender name is prominently placed, while the actual address is rather hidden.
Edit: This seems to only apply to posts made in groups.
What about triggering scam warning?