I have my desktop PC set to save emails on the server for 5 days.  I have my laptop and tablet set to save emails on the server.  When I view mail on my portable devices first then open the mail on the PC later the mail read on the portable units does not show up as it should, only new mail.  I can go to a webmail program and the email is there in the inbox as it should be.  And if I view mail on my Windows 8.1 smartphones the mail shows up again as it should on the desktops.

Any clue on why my mail is not showing up on the desktop after opening it on the laptop and tablet?