hello,
i'm doing pretty much the same as you.. I am making an emailing system where u can subscribe and unsubscribe from an emailgroup... If you make a mailing you have to specify an emailgroup you wish to address... I just step through my database and for every subscriber i just send an email, also with some extra tags so I can get some feedback (when opened, which links clicked) and some tags for unsubscribe and editing the subscribers info, and tags for inserting firstname, lastname and email address in email. I guess this is what u want to do..
I found an email class that made this all possible.. sending mails and inserting content.. send me an email if u want this class with some explanation
Greetz,
$nafu
PS: checking for bounces is not possible with this class, I still have to write a script that runs on the mailserver to check for bounces