The built in mail app should handle pop as well as exchange.
I currently have an Exchange account, an IMAP account and a hotmail (pop) account setup. The only bad part is the hotmail account doesnt sync what I have deleted so I have to delete them in the web interface even if I delete it on the iPad. This is a limitation on Hotmail's end though. I dont know of any app that can get around it.
The provided app handles pop accounts, but I cannot file e-mails. Everything must stay in the in-box or be deleted. So if I have an e-mail that I want to keep there's no way to file and find it later
Oh I see. Dont know of anything off-hand, but it very well may be out there.
If your service allows you to use IMAP instead of POP, you can have folders. My personal mail is with fastmail.fm they have free IMAP accounts I think, or you can pay for expanded storage. You can setup server side filing rules, alias address and all kind of cool stuff.
