Just helped someone out configuring Outlook on his laptop (which he had) and his new Desktop, Win 10. I got it all setup. He uses POP (and changing to IMAP would be a hassle as he has lots of folders and contacts in his PST).

Anyway, all works. except, even though both Mail Configurations say "LEAVE MESSAGES ON SERVER" it seems whichever one checks his mail, the messages that download into that Outlook will not download into Outlook on the other computer.

I have setup similar for many people in the past, and never ran into this issue. So I am wondering if it is just a Gmail thing. We did a test, I emailed him, it made it to Gmail server (message shows in Web Mail). Downloaded into his Desktop, but even when he forces send/receive on laptop, that message did not download to the laptop.

Also, on his phone he has gotten all the emails (but it is probably IMAP...how most phones normally function).

Any help would be most appreciated.