As the QA lead for Mozilla messaging I'm looking for a few users. These should be willing to spend 30 minutes to an hour reading test and entering test results in litmus, mozilla's test management software. Those test are there to make sure that we are not regressing from earlier releases there. There are a few hundred of these tests, splitting the work between participants is a very important key to a successful test run. The more testers the more coverage we get out of these tests. If you're interested in helping just drop me an email with your computer's operating system. I'll send details instructions when we have RC1 builds and that we are ready for testing.
I am willing to help perform some of these tests. I am a fan of supporting Open Source software and frequently beta test software. Please add me to your list of possible testers.