Setup a gmail account to send mail from the address you want.
Gmail has a 500 contact per email limit I think.
Better yet, sign up for google apps and use that:
http://www.google.com/apps/intl/en/b...profit%20gmail
Either way,
What I do is create a mailing list, and then copy all of the addresses over into a word editor. I find and replace all of the spaces with commas, and then copy that into a gmail compose message in the bcc area. Then I write the email and send it out.
Works for me.