Well, you have Interspire which is just amazing. Autoresponderplus has some good reviews around here and it is a lot cheaper than interspire. Google them both to see which one fits your needs the best and go from there.

One of the issue to be concerned with all if not most autoresponder is the possible loss if your e-mail account if you get scam complaints that is if they use your addresses...would be important to clarify... hope that helps.
Richard