At 01 Apr 2008 19:55:43 -0700 Robert A. Fink, M. D. wrote:

> When I read a piece of POP3 mail, I either save it to a folder or
> delete it from the server. Therefore, it is deleted and will not show
> up on the phone if I have read it on the computer, or vice versa.
>
> Correct?


This explains it better than I ever could:
http://www.imap.org/imap.vs.pop.brief.html, but essentially each device
keeps track of what POP mail it's downloaded but no device knows what the
others have done.

(Having said that, however, some "POP" services, like GMail or AOL, don't
follow the POP protocol and therefore don't play by the rules- they just
act like POP services to allow access by POP e-mail clients.)