For mass email, I would recommend not using Universal Email for a couple of reasons.
One, server companies typically prefer you use the sendmail function from PHP for mass mail rather than using account email protocol which is far more taxing on the server.
Two, Universal Email does not have any way to "throttle" the amount sent.
If you are determined to do this on your own server, Linecraft (help.php) does make a mass email extension that you can define the list based on a recordset and then set the interval for how many emails go out in each burst. I caan confirm that it works decent, but if you want some that works really well and has great tracking, then I would use a service like Mad Mimi (www.madmimi.com/). I swear by them... your emails will look awesome, you will have full reports of how many have read, what links were clicked and by who, and how many bounce. And the pricing is really really good in comparison to other similar providers.
Thanks, I'll check out madmini.com now.