How to Fix Error “Outlook Storage Full despite Deleting Everything”?

In Outlook, there is a defined size limit for mailbox storage. This mailbox size limit can be reduced/changed by administrators, depending on the users’ usage and company policies. When the mailbox reaches the defined mailbox limit, users start getting the ‘Your mailbox is almost full’ error message. In such a case, users need to reduce the mailbox size. The best option is to delete unnecessary or old emails and other mail items. 

However, sometimes, users get the error ‘Outlook storage is full’ despite deleting everything. This might happen due to various reasons. In this article, we will look into the reasons for the mailbox storage full error message and discuss the ways to reduce mailbox size to resolve the error.  In such situations, using an OST to PST converter can be highly effective. Converting the OST file to PST format and utilizing the software’s splitting feature helps manage oversized mailboxes by breaking down large PST files into smaller, more manageable sizes.

In this article, we will look into the reasons for the mailbox storage full error message and discuss ways to reduce mailbox size to resolve the error.

Reasons for Outlook Storage is Full Error despite Deleting Everything

Here are some common reasons behind the Outlook mailbox full error despite deleting everything from Outlook:

• Deleted emails and items may not have consumed much space. Hence, deleting these items didn’t reduce much storage.
• Outlook folders such as Sent Items, Drafts, Junk etc. are consuming a lot of space. 
• There are large attachments in emails, consuming significant storage space. 
• Unnecessary entries in Calendar, Tasks, and Notes.
• White space in Outlook data file.

Methods to Fix the Outlook Storage is Full despite Deleting Everything Issue

To resolve the Outlook storage is full issue, you need to reduce the mailbox/data file size. Here are some ways to reduce the mailbox/data file size. 

Method 1: Empty ‘Deleted Items’ or ‘Trash’ Folder 

In Outlook, deleted emails are moved to ‘Deleted Items’ or ‘Trash’ folder and remain there until the retention period expires. To reduce the storage space after deleting the emails, you need to also empty the ‘Deleted Items’ or ‘Trash’ folder. Follow the steps explained below:

• In your Outlook, go to the ‘Deleted Items’ or ‘Trash’ folder.
  
• Right-click on the folder and select the ‘Empty Folder’ option. 
• Confirm the action when prompted. 

You can also configure Outlook to empty the ‘Deleted Items’ folder automatically. Follow the steps given below:

• In Outlook, go to File, click on ‘Options’, and then select ‘Advanced’.
• In the ‘Outlook Options’ window, under ‘Outlook Start and Exit’, check the box in front of ‘Empty the Deleted Items folder when exiting Outlook’.
  
• Scroll down and then select ‘Prompt for confirmation before permanently deleting items’. 

You will get a prompt to empty the ‘Deleted Items’ folder every time you exit Outlook.

Method 2: Check Other Outlook Folders

It might happen that folders, like Junk Email, Drafts, etc. contain many items, consuming a lot of mailbox space. You can empty these folders to reduce the mailbox size. Go to the respective folder, right-click it, and then click the Empty Folder or Delete All option to delete all the items from the folder. This will help in reducing the mailbox size. 

Method 3: Remove Large Attachments

You can also check if you’ve emails with large attachments as they might be consuming significant storage space. To free up space in Outlook, you can save the attachments on local storage and then delete the emails. Follow these steps:

• Open Outlook on your system. Navigate to ‘Search Folders’ and right-click on it.
• Then, click on New Search Folder.
  
• In the window that opens, select the ‘Large Mail’ option under the ‘Organizing Mail’ section.
• Then, under the Customize Search Folder, choose a size in ‘Show mail at least this large’ field, and then click OK.
  
• Now, you will see a new folder (named Larger Than) is created under Search Folders.
  
• Select (press CTRL+A) all the messages in the folder and click the Delete key. This will delete all the large emails. 

Method 4: Archive Calendar Items

To reduce the mailbox size, you can also archive or delete the items from Calendar. To archive your calendar items, follow these steps:

• Open Outlook and go to ‘File’.
• Select ‘Clean Up Tools’ and then click on ‘Archive’.
• Select the ‘Archive this folder and subfolders’ option.
• From the list of folders, select ‘Calendar’.
• In the ‘Archive items older than’ field, enter/select a date. 
• 
• Now, click on the ‘Browse’ button to select the location to save the archive file and click OK.

Method 5: Compact the Outlook Data File 

To reduce the size of Outlook data file, you can also compact the data file. Follow the steps given below:

• Open Outlook and navigate to ‘File’.
• Select ‘Account Settings’ and then click on ‘Account Settings’.
• Now, select the ‘Data Files’ tab and choose the OST file you want to compact. Then, click on ‘Settings’.
• 
• In the Settings window, select the ‘Advanced’ tab, and then click on ‘Outlook Data File Settings’.
  
• Click ‘Compact Now.’ This will reduce the file size by removing unused (white) space.
• 

Method 7: Archive Old Emails 

You can also archive older emails and other mail items to reduce the size of mailbox/data file. Follow these steps to archive older items in Outlook:

• Open Outlook and navigate to ‘File’.
• Select ‘Info’ and click on ‘Tools’.
  
• Select ‘Clean Up Old Items’.
• Select the Archive this folder and all subfolders option and choose the folder you wish to archive.
• In the Archive items older than field, enter a date. Click OK.

Conclusion 

If you’re receiving the error message ‘Outlook storage full’ even after deleting older emails and other items in Outlook, then follow the methods mentioned in this article to reduce the mailbox/Outlook data file (OST) size. Since Outlook stores all the mailbox data in Outlook data file (.ost), you can compress or split the data file to reduce its size and resolve the error. The best way to compress or split large size OST file is by using an advanced third-party software, like Stellar Converter for OST – Technician. This software comes with different utilities that can help manage Outlook data files. You can use the tool to convert OST to PST file and save in the PST file. It also offers the option to split the resultant PST file into multiple smaller parts. You can use the compact option in the software to compress the converted OST file.