I've successfully used Outlook with POP3 Gmail for several years without any problems. I'm currently using Outlook 2010 on my PC.
A few weeks ago I bought a T-Mobile G2 (Android 2.1) smartphone and configured it to connect with one of my my Gmail accounts using POP3. All appeared to be working properly, with the same message headers showing up on both the G2 and in Outlook, and no problem downloading messages from Gmail. But then I noticed that if I opened a message on the G2, that message never showed up in my Inbox. Newer and older messages that I did not open with the G2 do get downloaded to my Inbox. It's as if Outlook thinks the opened message is not new, so it never gets downloaded to my PC from the server.
Is this a Gmail issue? Android? Outlook? How can I narrow it down?
How does Outlook know whether to download a message or not? I thought it would always download messages newer (by timestamp) than that last batch that came in.