Which Layout Are You Using?
The sorting options available to you and how you use them depends on which view you’re using in Mail. It offers two appearance options: default and classic. The classic layout shows all of your emails on single lines at the top of the screen with the contents of the message you’ve selected beneath them. The default layout includes preview text and puts the full emails in a pane to the right. Here’s how to switch between the two.
Change or Reverse the Mail Sorting Order in Default Layout
To sort the messages in any folder in OS X Mail using one of several criteria:
Change or Reverse the Mail Sorting Order in Classic Layout
To sort your messages in Mac OS X Mail with classic layout enabled:
Attachments: separate messages with files attached from ones that don’t. Date: sort emails based on when you received them. Flags: separate messages you’ve flagged from ones you haven’t. From: sort emails based on who sent them. Size: arrange messages based on how much space they take up. Subject: sort messages alphabetically by subject line. To: list emails based on whom they’re addressed to. Unread: separate messages you’ve read from ones you haven’t.
How to Sort OS X Mail Using the Menu
Alternatively, you can quickly sort in both layouts by opening the View menu and selecting Sort By. This menu includes both sorting criteria and the ascending/descending options.