Over the last couple of years I have recommended GAFYD many times. In fact, I use GAFYD for databack.com email because the features I get free exceed what I can offer on my own servers! Check it out here.
“Is Gmail down for just me or for everyone?” http://goo.gl/zvmW
Every message you send to your newsletter list should offer an unsubscribe option. It’s easy to include such a link – please see http://wiki.databack.com/OneClickUnsubscribe/
This page also provides an easy way for subscribers to CHANGE their address.
NOTE: This is only for newsletter lists, NOT discussion lists.