Apple Mail, which is the default Mail application on Mac OS X, offers a variety of features for sorting your emails. Between mailboxes, smart mailboxes, folders and viewing settings, checking your email can get a little complicated. If you have lots of messages and don't necessarily read them in order, you can end up with unread messages spread out all over the place. Luckily, Apple Mail provides a viewing option to see only your unread messages.
Open Apple Mail on your Mac.
Click the arrow next to "Sort by Date," located just above your messages in the left column.
Click "Unread" to sort your email by unread messages at the top.