Outlook Mailbox Full

Outlook mailboxes can store up to 49.5GB of emails by default, and thus will need manually clearing out as Outlook will not delete any emails automatically no matter how old they are. This can also easily fill up if emails contain many attachments, as attachment sizes are included in this limit. Fortunately, clearing your mailbox is fairly simple. This guide will only cover Outlook Classic.

To see your current mailbox storage, check File --> Mailbox Settings. I have 48.6GB free

To clear up your mailbox, you normally have 3 options

1. Remove old emails
2. Remove emails with attachments larger than i.e. 5MB
3. Remove all unsent drafts

Using a combined search criteria of anything sent or received in 2024 that is over 1MB in size, I will provide 2 methods of easily finding these items within your mailbox so that they can be removed. It's important to note that finding these items is fairly simple, Outlook may take a while to process the deletion of items depending on how many there are. For example, if you're trying to remove all items from a single year, there may be a significant impact on Outlook performance as it will be processing the removal of (tens of) thousands of emails

Important - We keep a comprehensive email archive record of everything sent & received to all inboxes Beginning March 2018. Everything after then can be found upon a request to IT, so don't worry about keeping anything 'just in case' you need it in the future. If you are unsure of performing the below actions, let us know and we will help!

Option 1 - Using the Mailbox Clean-up tool (Simplest

File --> Tools --> Mailbox Clean-up

Click Find in the second section and this will bring up the search tool. Click on the Advanced section to open the search criteria entry. To add a Criteria, begin with the Field dropdown menu

Filter #1 - search all emails in 2024 (Outlook is in the US MM/DD/YYYY format)

Filter #2 - search for anything larger than 1MB (This value is in Bytes, see link to convert Megabytes to Bytes MB to Bytes Conversion Megabytes to Bytes Calculator)

Once these are both selected by pressing the Add to List button, Click Find Now to perform the search. Note - This search is just for Received items, as per Filter #1. To search in Sent Items, simply click the Received search criteria, Click Remove and then Click the Field dropdown --> Frequently Used Field --> Sent

Then, you would select one of these emails, press Ctrl + A to select all and then Left click --> Delete to move all the items into your Recycle bin, at which point you can then remove them all from the Recycling bin to permanently remove them

Option 2 - Criteria in the Search bar

The below is the criteria to use in the search bar at the top of Outlook. 

(size:>1048576) AND (sent:>=01/01/2024 AND sent:<=12/31/2024)

(size:>1048576) AND (received:>=01/01/2024 AND received:<=12/31/2024)

Like above, this will scan for items matching the criteria of being within 2024 and being larger than 1MB. You'd just then select one --> Ctrl + A to select all --> Delete to remove to Deleted Items --> Remove them from here to permanently delete