Thank you for the feedback sfrassanito. :)
I had totally missed the header at the wp_mail_smtp.php :(
You seem to have the whole thing working out.
So could you please clarify/correct me if and where I am wrong with the 4 different scenarios? When working with a multisite, I place the appropriate lines (...firstname.lastname@example.org...) at the config file and :...
1. Emails sent from the network admin (welcome, new site, etc) or the main site (new user, lost password, etc) will be send from email@example.com as long as both the emails under "network settings" and "settings->general" are the same. Correct?
2. Someone from site34 (it is a multisite remember) has his email (under settings-->general) at: firstname.lastname@example.org. What happens when a new member registers at his site? Or asks for a new password?
3. Someone from site75 has her email at email@example.com But wants to use her gmail account at firstname.lastname@example.org. Callum mentions:
...I recommend if using the plugin on a multi-site setup, put your settings in wp-config.php and then disable the admin menu
How can I "disable the admin menu" so she canNOT use her gmail account?
Moving the whole folder wp-mail-smtp to mu-plugins will do the trick? Must I do something else?
4. Site99 is a mapped domain. So it is now newsite.biz and their email is email@example.com. What happens then?
I know it is a lot. But I thought I give it a try. :)
Any help is highly appreciated.
Thank you in advance