What do you use to send emails to all your users?
jaddison: For our http://www.snapact.com/ startup, we currently use http://www.constantcontact.com/ for monthly newsletters.  I'd also be interested in learning what other people use.User signup verification and the like we use an internal mail server (Postfix on Linux) - keep in mind that going your own route requires knowledge of how spam flagging works, or you'll wind up getting caught in filters all the time.  SPF, DomainKeys, Reverse DNS settings and more.Good fun all around.