[php] Sending mass email using PHP

Why don't you rather use phplist? It's also built on top of PHP Mailer and a lot of industry leaders are using it. I've used it myself a couple of times to send out bulk mails to my clients. The nice thing about phplist is that you can throttle your messages on a domain level plus a time limit level.

What we've also done with a couple of internal capture systems we've got was to push our user base to the mailling list and then have a cron entry triggering a given mail each day. The possibilities are endless, that's the awesome thing about open source!