Every few months or so, I like to send out an e-bulletin to forum members. However, the vBulletin built-in script just isn't robust enough as it constantly will time out every few pages. I've also tried sending mail directly from Mirosoft Outlook, but the sheer volume of emails made that nearly impossible as well.

I'm looking for a mailing list script that will let me throw a good 20K addresses at it - and it will run behind the scenes on my server. In other words, I don't want the actual sending to be via a web application that can continuously time out - nor do I want to have to keep a webpage open for so long.

Any recommendations?