I have a site with a few thousand customers, and we'd like to be able to mail them all at once with information about site updates, etc. I've been trying to do it with PHPmailer, but it's really not well suited for this -- I'm getting time out problems, and adding all the emails to the BCC field makes it so that the email won't send (there's a limit on BCCs on our server). Upping our time limit for scripts would only be a temporary solution, since as our site grows, and our customer base increases, we'd have to keep upping that limit to ridiculous amounts.
What I'd like to find is a bulk mailing script that will tie into OUR database -- I've looked at stuff like PHPlist, which is great, but appears to use it's own database. I need something I can plug in easily into our own site structure and database. Any suggestions?