I've just put this up on one of my other blogs, didn't want to say the same again here, so click through to find out more:
http://acmeweblog.com/uncategorized/how-to-choose-the-best-autoresponder-deliverability-matters/
(An autoresponder is a program feature that sends an automated reply to incoming email. For example, when customers send email to your sales@yourdomain.com address, a standard message could be sent back to them. It also lets you send out regular messages to a list of subscribers as well as ad hoc 'broadcast' messages.)
Success Online!
LyndaH