I know mail is in beta. But please keep an eye on this function as I see others have some problems too; however, most seem to have problems with SMTP, not POP.
What I'm finding here is that POP works intermittently; most of the time it says that 0 mails received, when in fact there are several on the server. Then all of a sudden, it works again and retrieves the mails. Since there's no error reported, there is no log of the event.
If I can help more, please let me know. I am a programmer too, only a little bit of PHP; mostly Delphi/ASM etc.
Al.