Find the current size of your mailbox:
Right click the root of your mailbox name (usually this is called "Mailbox - <your name>")
Click Properties for "Mailbox - <your name>".
Click the Folder Size button
Click on the 'Server Data' tab to obtain the size of your mailbox items stored on the
Exchange server. The program runs to verify size of your mailbox.
Note: Please be patient while the program runs. It may take several minutes. If the
program starts running before you get a chance to click on the Server Data tab, click
the Cancel button. Then proceed.
The total size of your mailbox is displayed in kilobytes.
1 megabyte (MB) = 1,024 kilobytes (KB)
1 gigabyte (GB) = 1,024 megabytes (MB) = 1,048,576 kilobytes (KB)