Resolve Outlook Mailbox Full After Deleting Everything Error

Published By siddharth

Approved By Anuraag Singh

Published On March 25th, 2026

Reading Time 7 Minutes Reading

Category Outlook

Are you facing this “Outlook mailbox full after deleting everything” error? No problem, you aren’t alone. Multiple users wondered if they would clean up emails so they could prevent Outlook mailbox is full issue, but still encountered it. This issue occurs again when we delete any data, and we thought that it was eliminated, but it’s not permanently deleted from mailbox, which becomes necessary to remove from that.

So, in this article, we are going to discuss what to do when Outlook mailbox full even after deleting everything. We will fix this error by using 7 proven fixes by understanding the root cause of problem and its solutions. Let’s walk through the article.

What Happens When Outlook Mailbox Is Full?

If one can understand the cause of this frustrating problem, then it can help one to enhance Outlook performance. Let’s take a look at them.

• User might stop getting new emails.
• You may fail at sending any message.
• Performance or Speed of Outlook might slow down.
• Any critical emails can easily bounce back to sender.

Such issues will make it necessary to fix the error instantly. But how will a user resolve it? Let’s walk through the following section.

Let’s quickly understand them with an explanation.

Method 1: Clean Deleted Items Folder

Steps to follow:

1. Navigate to Deleted Items.
2. Select Empty Folder by right-click.
3. And Confirm Deleting.

It will make sure that emails are also removed permanently from junk folder.

Method 2: Try Outlook Clean-Up Tool

MS Outlook offers its built-in option, that helps to free up space from folders, subfolders, and conversations. To use this feature, follow these steps:

1. Navigate to File, then Tools, and finally on Mailbox Cleanup.
2. Check Mailbox Size
3. Search for old and oversized emails.
4. And remove unwanted items.

This is a very simple method to handle your Outlook mailbox. But sometimes, mailbox can also be full due to duplicates in it. This built-in feature can be useful only to some extent. In such cases, we recommend using a trusted software, which is SysTools PST Duplicate Items Remover Tool. This will help you in eliminating all duplicates from mailbox automatically and increase your mailbox storage space.

Method 3: Empty Recoverable Items Folder

One should always check and remove any data that remains in hidden folder. Follow the steps to eliminate.

Steps:

1. Go to Deleted Items.
2. Press on Recover Deleted Items From Server.
3. Select complete data and remove them permanently.

It’s essential to completely resolve the root cause of the Outlook mailbox full after deleting everything.

Method 4: Try Shift+Delete to Remove Permanently

Users can bypass the deleted items folder step if they use this method:

• Choose all emails.
• Hold Shift and delete button together.

It will remove all unnecessary emails quickly.

Method 5: Remove Large Attachments

Attachments are the most storage space-consuming item. If they are not of use or unwanted, then you should remove them from mailbox.

• One can search the messages by size.
• Save them in your local system as a backup.
• Clear all attachments from emails.

Cleaning of unnecessary or large attachments will help to reduce mailbox size.

Method 6: Enable Auto Archive Option

Users can enable autoarchive feature to transfer older messages to different data files.

Steps:

1. Navigate to File, then tap Options, and finally on Advanced tab.
2. Enable Auto Archive feature.
3. Set archive frequency according to your use.

Enabling option will avoid the Outlook mailbox is full error.

Method 7: Compact Data File

After using all methods above, if your issue is still not fixed, then there is a simple solution, which is to shrink your file size. This will help you lessen the original file size, which enhances Outlook productivity.

Steps:

1. Go to File, then tap on Account Settings and finally hit Data Files.
2. Choose your PST file, which you want to reduce in size.
3. Click on Settings and press Compact Now button.

Conclusion

In the informative article, we’ve discovered how to fix Outlook mailbox full after deleting everything using 7 proven steps. This error can be caused by various reasons, but we’ve listed all solutions to resolve Outlook Mailbox is full issue. One can effectively get rid of this recurring problem by following our above step guide. Don’t forget to clear deleted items or hidden folders, as it’ll help to speed up Outlook performance.