updated 05:10 pm EST, Mon February 3, 2014
Email client not fetching new messages as intended
Apple has posted a new support article explaining a temporary workaround for people having trouble with Mail in OS X Mavericks. When the OS was first released, some users had problems with Mail like the app failing to fetch messages or properly move and delete them. Many of those glitches were fixed by the release of OS X 10.9.1, but some people are still having trouble getting the app to fetch messages without quitting and restarting.
The article primarily asks people to go into the Mailbox menu, click Take All Accounts Offline, and then Get All New Mail whenever they want to refresh. As a shortcut, Apple suggests going into the View menu and selecting Customize Toolbar, where they can then drag the Take All Accounts Offline and Get All New Mail buttons in for easy access later.
Apple hasn't said when a permanent fix will arrive, but betas of OS X 10.9.2 have come with notes asking developers to test Mail.