Outlook Mailbox Size
This is a short tutorial on how to view the mailbox size in Microsoft Outlook 2013. It breaks it down by folders.
In Microsoft Outlook 2013, click File.
Under Cleanup Tools click on Mailbox Cleanup…
Click on View Mailbox Size.
The list that presents itself should let you see what’s holding the most data.
You can also right click on a folder in your Inbox, go to properties and click on folder size.
You can also read Microsoft’s article “Manage your mailbox I: Find its size and trim it down.”