When I write an email to a friend or am replying to an email from someone I know well I always put their name after Bonjour.
Most of the time what I receive just says Bonjour and NOT Bonjour Sue.
I find that so abrupt and unfriendly. But am I in fact being too familiar (even to a friend) if I add their name?
If its someone you know then its OK to put their name. The very rich Parisien lady I worked for always put Bonjour and then my name, it made relations between us very friendly in so much as she never used my title or surname.
I receive both, but perhaps the business ones are more likely to start “Bonjour”.
But these are good acquaintances at the very least - members of our photo club. 