How to Fix The Outlook Mailbox is Full error

If you get a ton of emails in your main account, it is evident that Outlook will throw up this prompt “The Outlook mailbox is full” at least once. There is a certain limit to how much storage Outlook can use to store up emails. There are a ton of ways you can fix this problem on your Outlook client. So, without wasting any more time, follow these steps minutely to free up Outlook.

Fix 1 – Archive the mails

Archive your old emails. This way, you will save a lot of space in Outlook.

Step 1 – Open Outlook, and click “File“.

Step 2 – You have to go to the “Info” section.

Step 3 – Then, click “Tools 🔽” and tap the “Clean Up old items…” option.

If you are using Outlook 2013 or older, go this way –

File > Info > Cleanup Tools > Archive


clean up old min

Step 4 – Select the folder that you want to archive (like the Inbox or the Sent). Then, select the “Archive this folder and all subfolders” option.

Step 5  Set the Archive items older than: to a specific date that you want. It is recommended that you choose a date at least three months prior to the working date.


archive older items min


Step 6 – Make sure to check the “Include items with “Do not AutoArchive”” box to archive only specific files and folders.

Step 7 – Finally, click “OK” to start the process.


include items with do not autoarchive min


Close and relaunch the Outlook client.


Fix 2 – Clear out the Deleted items folder

Deleted items folder acts as the Recycle Bin for Outlook. Make sure Outlook clears it whenever you exit the client.

Step 1 – On the Outlook home page, open the “File” option.

Step 2 – Then, tap “Options“.


options min 2


Step 3 – On the Outlook Options tab, choose the “Advanced” zone.

Step 4 – Go to the Outlook start and exit section. Check the “Empty Deleted Items folder when exiting Outlook” box.

Step 5 – Then, click the “OK” button to save the change.


empty deleted files min


This way, you can make sure Outlook gets cleaned every time you delete some big emails.


Fix 3 – Store the attachments outside

If some email has big attachments you can just store those in another vacant drive. You will save a lot of space in your system drive this way.

Step 1 – Launch Outlook. Open the mail that has the attachment.

Step 2 – Then, click the arrow sign 🔽 beside that attachment and tap “Save as…“.


save the attachment min


Now, go to a drive of your choice and save the large attachment there. Continue this process with every big attachment to save up more space in the future.


Fix 4 – Cleanup the mailbox

Clear the Deleted Item files in Outlook.

Step 1 – After opening Outlook, go to “Files“. Click “Info“.

Step 2 – Then, tap “Tools” and click “Mailbox Cleanup” to clean up all the old emails.


mailbox cleanup min


Step 3 – On the Mailbox Cleanup page, tap “Empty” to empty the mailbox completely.

Step 4 Additionally, you can use the “View Deleted items Size…” to view the size of the deleted mail.


empt the mailbox min


Close the Outlook page. Then, restart your computer. Check if this solves.


Fix 5 – Clear out all the big mail

You can create a filter to store the big emails on Outlook. This way, deleting those emails will free up more space in Outlook.

Step 1 – Find your email address on the left pane on the left ribbon to find the “Search folders“.

Step 2 – Click that once and quickly tap “New Search Folder…” to open it up.


new search folders min


Step 3 – Slowly scroll down and select “Large mail“.

The default filter size is “100 KB“. But you can change it using the “Choose” option. Set your desired filter limit and apply it to the emails.

Step 4 – Then, click “OK“.


see the larger folder min


Now, you will see a new folder called “Larger Than” to find out all the large emails.


Fix 6 – Free up more SSD space

Clear up more space in your C drive.

Step 1 – Using the Win+R keys together.

Step 2 – Input this and hit Enter.



cleanmgr min 1


Step 3 – Make sure the “C:” drive is selected and tap “OK“.


select the drive c min


Step 4 – Check all the items that you can find there.

Step 5 – Then, click “OK” to start the process.

Step 6 – A warning message will appear. Tap “Delete Files”.


select all and ok min


Wait for Windows to clear up all the junk files. Check if this works.