Good idea, but please please be careful and take the necessary precautions before you send your IP/domain name to the abyss of spam trapping blackholes. If you

Good idea, but please please be careful and take the necessary precautions before you send your IP/domain name to the abyss of spam trapping blackholes. If you're sending more than 200 messages to the big 4 (Gmail, Yahoo, Hotmail and AOL) take the time to REGISTER with them first and tell them about your messaging habits. Do not change the from FROM field ever! Try to minimize content changes between messages; rewrite the URLs in message bodies for tracking purposes. Don't send a message to an unverified mailbox. Make sure your users consent to receiving your message and you have a way to prove this (a check box on the post sign up screen.) Do not use a misbehaving SMTP server that doesn't accept returned messages and other housekeeping communication; gmail will say "message undeliverable" the first time around and look back at you to see if you acknowledge this, or it might not confirm delivery for a while, to see if you're a phantom smtpd who would disappear after an hour. Get DomainKeys, SPF and other credentials you need. Do all your mailing from ONE domain name, mail.example.com and make sure you have backup servers as well. Good luck. P.S. Postfix has various mailing list and newsletter management addons. Qmail was written JUST for that purpose.