I coded an html email that I tested in Gmail, YahooMail,Thunderbird and Outlook 2003, as well as IE and Firefox. What other email applications should I test it in, and how can I get these applications on my pc? Thanks.

personally i think you should be focusing more on mobile browsers (iphones, blackberry, android), fair enough the browse on a pc and mac are still the major player,
The world is shifting, and fast, things like the galaxy and ipad, make sure your email displays correctly in different resolutions as well as different applications.

Hope this helps

Thanks. Is there a way to check that from my pc? (Like an online service or something)