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Microsoft Outlook mailbox is not shrinking as expected

Find out how to accurately gauge your mailbox size in Microsoft Outlook after cleanup by following these steps.

In Outlook Mailbox Cleanup, I clicked View Mailbox Size to learn that my mailbox is 175 MB and is near its limit. After deleting 110 MB from my Sent Items folder, I still found that my mailbox was at 175 MB and not the 65 MB I was expecting. How can I accurately determine how much room is left in my mailbox after I clean it up?
You did not mention whether or not you emptied your deleted items folder. If not, you should purge the items in there before you'll see the size of your mailbox come down as expected. If you've emptied the deleted items folder I would try navigating to the Folder List icon in the left hand pane of Microsoft Outlook. Look for a folder at the bottom of your mailbox called Sync Issues. You'll likely find a lot of messages in the folder. Right-click and use Folder Size to see how large this folder is.

I 've seen numerous instances where this folder contains 50% of the size of a mailbox. My recommendation is to delete the messages in here, then re-calculate the overall size of your mailbox to see if it reduces the size as expected.

Finally, if neither of those ideas worked I would right-click Mailbox in Outlook and choose Folder Size. From there, meticulously scan through the size of each folder. You'll probably find some surprises along the way, but by stepping through the list of folders and associated sizes you should be able to find the source of your problem.

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