Technically, the operating system doesn't check email. The apps that are loaded onto the OS can check email, but I think most email apps check the email chronologically.
I use K9 with a POP3 account and haven't had any problems at all.
I'd love to know what you're doing differently than myself.
I only see the inbox and trash. I don't have a sent folder, drafts, outbox, etc.
Yeah, I was wondering what you meant by only 2 mailboxes. So you're checking one mailbox but the
folders aren't showing up, right?
That's kinda weird because when I set up a pop account in K9, it automatically shows sent, drafts, outbox. Anyway, what you can try is going to your "Folders" view in K9 (where you see the list of folders), then hit the phone's menu key, hit "Folders" (again) and a menu will pop up. The first thing to try is "Display all folders". Then go to menu > Folders again and choose "Refresh folders". If that doesn't do it, I don't know what will. It's kinda strange that you'd have to do that for POP3 because as I said, it always worked by default for me. If it works, the display of the folders will stick and you'll be good to go.
Hm, I wonder if in settings you had set "Folders to display" to "Only 1st Class folders" or something.