What email sending services do you use?

We have a large list of people waiting for invite codes, but we're having problems with our mass emails getting caught by spam filters. We're looking for a service that will help us see how many emails are bouncing or not, as well as sending emails with domainkeys authentication. We've looked at http://www.industrymailout.com, http://www.campaigner.com/, http://www.jangomail.com/, http://www.authsmtp.com. What do you use for sending mass emails? Any tips for getting past the spam filters to our legitimate subscribers?