Your mailboxes can be sorted according to a variety of critieria. Sorting messages can be a very useful way to manage your mailbox helping you retain what is important and delete clutter. For example, you could sort your mailbox by size. This would quickly indicate the largest messages in your mailbox. Moving these items to personal folders or deleting them can help address the size of your mailbox. Sorting by date would allow you to address older items that have been sitting in your mailbox.
To change the sorting order of your mailbox, go to View > Arrange By. This menu will show all the sorting options available to you.
