PHPList is a good, free mailing software - its usually included in fantastico

http://www.phplist.com/

i've heard of people modifying it to use postgre, but i believe it only comes with support for mysql out of the box

Thank you, PHPList is kind of what we decided to use if we have to manually import.

After you get the machinery to pump out the mail, there is the issue of getting it through spam filters. I have had numerous problems when sending emails from my own domain. It is all too easy to get on various blacklists even if you are extremely well behaved.