How to Fix “Outlook Mailbox Is Full Can’t Send Messages” Error?

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The Outlook Mailbox might increase in size making it harder to send or receive emails when you deal with high emails inflow or get emails that have large attachments, or this sometimes might be due to PST file corruption. To resolve the issue follow the possible troubleshooting ways given in the article or download the Remo Repair PST tool to resolve any issue with PST corruption easily.

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Have you not been able to send or receive emails because of this “Outlook storage full” error? Although Microsoft has increased PST size in the latest Outlook versions; many users still encounter this error message saying, "Your Mailbox is full, you can't send messages". No worries! After going through this article, you will be able to reduce the size of the Outlook mailbox and send and receive new emails again like before.

Outlook mailbox is full

Why Does it Say My Email Mailbox is Full?

There could be several reasons why your Outlook storage could appear as full. We have listed a few common reasons below-

1. Outlook is running Low on storage

Outlook saying Mailbox is Full error message generally occurs when the PST file reached its maximum storage limit. Outlook provides 15GB of free space with each account. Regular and consistent usage over an extensive period of time could cause you to use up all your Outlook storage. 

2. Excessive Cache and Junk data

Apart from your main data, you also have your junk or temporary data. Since Junk and cache data or not readily visible, they often go unnoticed and accumulate unbeknownst to the user. If your Outlook junk filter does not work, there are ways to fix it.

3. Third-Party Add-Ins

Third-party add-ins on Outlook could cause logical issues that could present themselves in the form of a storage problem. However, you can easily remove third-party add-ins and check if the problem persists.

4. Application bugs and logical errors

New major Outlook updates could come with a few bugs that could take the form of a storage error. If this is the case, then there is a good chance a patch will be released soon.

What Happens If An Outlook Mailbox Exceeds The Limit?

  • Low productivity, Outlook might hang occasionally 
  • PST file might get corrupt because of a large mailbox data
  • Outlook data loss
  • Unable to send or receive new emails
  • Might cause Mailbox corruption.

What Causes the Corruption of The Outlook Mailbox?

You should be aware that MS Outlook stores your data in two different types of PST files. Up to 2 GB of data might be saved in the ANSI PST format for Outlook versions 2002 and older. Furthermore, Unicode PST files with a bigger storage capacity of up to 20 GB were used by Outlook versions 2003 through 2007. In contrast, the Unicode PST files in the most recent versions of MS Outlook (2010), (2013), (2016), 2019 and 2021 can store up to 50 GB of data per file. If Outlook exceeds this size it might cause Outlook mailbox corruption and same may cause Mailbox full error.

How Do I Fix Outlook Mailbox Full Error?

Outlook mailbox quota exceeds after frequently sending and receiving emails for a certain period of time. It increases the size of Outlook Mailbox and occurs more frequently with users with emails that consist of media files like photos, and templates that are of large size. Here are a few methods to quickly reduce the size of Outlook Mailbox:

1. Delete Large Emails and Attachments:

  • Open Outlook and click on the Home tab scroll down to select Search Folder.
  • Click on New Search Folder.
  • Scroll down and under Organizing Mail click on Large Mail
  • Then click on Choose under Customize Search Folder.
  • Specify the size in the ‘Show mail greater than’ box and click OK to continue.
  • Click on OK again. A new folder named ‘Larger Than xyz KB’ will be created under Search Folders. Now the folder will get updated with the mails of the size that you have specified automatically.
  • Then open this folder and delete all unnecessary emails. 

2. Cleanup Tools Feature to Reduce Outlook Mailbox Size:

  • Open Outlook and go to the Files tab and click on Info.
  • Under the Info, tab click on Tools > Mailbox Cleanup.
  • From here you can select the items older than 3 to 4 months and whose size is more than 1 or 2 MB.
  • Click on the Find button, delete all the items which are no longer needed.
  • Then delete the space occupied by Empty Deleted Items.
  • Again open the Mailbox Cleanup toolbox.
  • You will see a button to View Deleted Items Size.
  • Click on Empty to permanently delete these items and create space for new messages.

3. Archive Older Items Using AutoArchive:

Periodically archiving your Outlook folders will keep the mailbox size small. You can create the archive.pst file that can be updated at a specified location according to your requirement, usually your local hard drive. This is useful because the archived items will be removed from your Outlook mailbox hence reducing the size and moving to the archive file based on the settings you determine. 

Microsoft Outlook includes an AutoArchive feature to archive the old or unrequired PST file items. Following are the steps to perform this.

  • Open the Microsoft Outlook application.
  • Navigate to Files>Options>Advanced.
  • Navigate to the AutoArchive section and click on the box saying AutoArchive Settings under it.
  • Now select the checkbox saying Run AutoArchive every day and provide the number of days as an interval for the regular automatic archiving process.
  • Click on OK.

4. Compress Outlook Files Using Compact

Outlook gives you the option of compressing the data files manually. This helps in restoring some extra space in the mailbox. Before starting the procedure, delete the items that are not required. Go to the File tab and click on Tools. Click on the Deleted Items folder and then click on Yes and permanently delete the Deleted Items folder. Then follow the steps given below:

  • In the File tab, select Account Settings and then click on Account Settings.
  • Then click on the Data Files tab, select the PST file to compact, and then click Settings.
  • Then click on Compact Now.

Hopefully, the above-mentioned solutions will help you in keeping the Outlook Mailbox compact and will not reach its maximum storage quota.

However, if the error keeps popping up even after deleting unnecessary data, it can be because of mailbox corruption. PST file size is one of the main culprits behind Outlook mailbox damage. This happens because working with an oversized PST file often leads to crashes and corruption of the database. 

But there are more reasons as well that can cause PST file corruption. The most common ones are sudden shutdown, power failure, abrupt closing of Outlook applications, software issues, hard drive failure, or virus infection.

Thus to rectify the Outlook mailbox full error, if the mailbox is corrupt, you will have to repair the Outlook data file. Repairing the data file will stop the error, and you will be able to resume communication via your MS Outlook account. 

Did you know that Outlook has a built-in inbox repair tool? This tool can help diagnose and repair any damage to your mailbox. However, if the corruption is severe, it's best to use a professional PST repair tool such as Remo PST Repair. It's important to use a reliable PST repair tool to avoid the risk of losing important Outlook data. 

Remo PST Repair is a highly-rated Outlook PST Repair Tool that can easily repair damaged PST files. If you wish to repair yours today, you can download now!

5. Use a PST Repair Tool to Fix Corrupt Outlook Mailbox

  • Download the Remo PST Tool for free and recover and repair corrupt Outlook Mailbox. 
  • Launch the Remo PST Repair tool, and select from the three options
  • Next, you can choose between two scan options Smart Scan and Normal Scan
click-on-repair-to- rectify-error
  • Click on Repair to start the PST repair process. After completion of the repair process, you can Preview the repaired PST file in the Outlook-styled browser.
  • Once the repairing process is successfully done, activate the tool and save the repaired PST file.
  • Watch the video tutorial to Repair the PST file without any hassle.
Watch the video tutorial to Repair the PST file without any hassle.
Video tutorial to Repair the PST file using Remo PST Repair

After fixing the corruption, you can go ahead and reduce the size of the mailbox using the above-mentioned methods. This will prevent your mailbox from getting corrupted in the future because of the oversized mailbox data. 

Tips For a Clutter-free Outlook

Apart from resorting to a thorough Outlook mailbox cleanup and related methods when your mailbox is full, there are ways or habits that you can adopt to prevent your Outlook mail storage from filling up. We have mentioned a few methods below-

1. Make Use of Auto Delete

You can allow Outlook to delete unwanted mail from unknown contacts. This should prevent your Outlook mailbox from filling up. You can do so by following the instructions below.

  • Open File, and select Options.
  • In the advanced tab, check the box to enable the Empty Deleted Items folder when exiting Outlook.
  • Click on OK to enable changes.

2. Save Outlook Attachments to Onedrive

Attachments often occupy a good portion of your Outlook storage; saving them using Onedrive will help prevent the “Outlook mailbox full error”. You can Save Outlook attachments to Onedrive by following the instructions given below-

  • Open Outlook, Next to the Inbox title, locate the filter button.
  • Click on the filter button to access the drop-down list and select By Size.
  • Open the Large Outlook Mails that have attachments and Click on Save to OneDrive.
  • After Saving, delete the attachment from Outlook.

3. Store Attachments Outside Outlook

Saving Large attachments on Outlook Can cause your mailbox to fill up fast. Instead, you download and save your Attachments in a new folder and free up space. By doing so, you won't have to deal with an Outlook storage full error in the long run.

Wrapping Up:

As the size of the mailbox increases, the probability of the mailbox becoming corrupt also increases. The specific size limitations of PST file is one of the major cause of Outlook corruption. Thus, if you encounter the issue of an oversized Outlook mailbox, Follow up on this article and keep the Outlook mailbox within its size limits also, use the automated tool Remo Repair PST as a backup plan to repair the Outlook and Outlook recover data safely.

Frequently Asked Questions:

How do I increase my Outlook mailbox to 100GB?

When the mailbox capacity surpasses 50 GB, the user has only two options: upgrade the Office 365 subscription or erase data from the mailbox. For many people, erasing data is not always an option. They can buy a subscription and increase the file size to 100 GB. Also, because of the rising prices, not every subscriber wants to upgrade the subscription plan, they can always erase data to reduce size.

How to check the size of your Outlook Mailbox?

Trying to figure out how much room you have left can be a little tricky. Go to Mail Inbox View > Folder > Folder Properties > Folder Size to find it out. The size will be displayed in kilobytes.

How do I clean out my entire Outlook mailbox?

Clean Up Conversation is a program that helps you organize your email discussions and reduce the number of messages in your inbox.
1. Choose an email conversation that needs to be cleaned up.
2. Select Next and click on Delete > Clean Up Conversation. You may also clear out entire Folders using this feature.
3. If prompted, select Clean Up to confirm. The emails are transferred to the Deleted Items folder.

About the Author: Tony Landry

Tony Landry is a Web Content Editor at Remo Software. He loves to write, edit, and manage content for users trying to troubleshoot and fix problems on Windows, Outlook, storage drives, and Cloud storage networks. With an aptitude that transcends writing, Tony is recognized as a Microsoft Outlook, Word, and PowerPoint expert. His comprehensive solutions…