How to Reduce Outlook Mailbox Size Without Losing Emails?

Why Users Might Need to Reduce Outlook Mailbox Size? 

There are multiple reasons why a user would need to reduce their Outlook Mailbox size, but the most important ones are: 

1. To avoid the “Mailbox Full” warning & continue sending or receiving new emails.
2. For improving Outlook’s performance and preventing its lagging.
3. To reduce the chances of PST/OST file corruption.
4. The user might want to speed up the syncing and backup processes.
5. To keep emails organized and make mailbox management easier.

Considering these reasons, it becomes important for you to reduce the Outlook Mailbox Size. You can refer to and try using the manual methods below. And, in case none of those methods help you, you can use the automated software below.  

5 Effective Methods to Reduce Outlook Mailbox Size

Now, let’s start the process of reducing mailbox size, using the five methods below.

Method 1: Deleting Unnecessary Data

In case you have some unnecessary emails or attachments in your Outlook, keeping them as they are is a waste of storage. Therefore, you’d better delete them only, using the steps below.  

1. Start the MS Outlook application and open your account.
2. Then, find your desired emails and attachments to delete. 
3. Next, delete the unwanted emails and attachments.
4. After that, simply go to your Trash folder.
5. And delete all your unimportant emails permanently. 

Cons: This method is very time-consuming and may cause some data loss. So, if you want, you can proceed further. 

Method 2: Archive Old Emails

Rohit was a Senior Marketing Executive who had a large number of emails in Outlook, but she couldn’t delete them as she could use them for future reference. In such a situation, you can archive your emails to separate PST files instead of deleting them. 

1. Start MS Outlook & click on the File tab.
2. Navigate to Info >> Tools >> Clean Up Old Items.
3. Then, Select Archive this folder & all subfolders.
4. After that, choose the folder you want to archive.
5. Pick a location to save the archived emails.
6. Finally, click OK to start the archiving process.

Cons: Archived emails are saved in separate folders and are not deleted from Outlook. This process is manual unless AutoArchive is enabled. In case, Outlook Archive Not Reducing Mailbox Size, you can move ahead with the next fix provided. 

Method 3: Using the Outlook Cleanup Tool

Outlook Mailbox Cleanup is a built-in feature provided by Microsoft for clearing the mailbox. 

1. Launch MS Outlook on your PC & click the File tab.
2. Then, Go to Tools >> Mailbox Cleanup.
3. You can click View Mailbox Size to see folder-wise storage usage.
4. Now, you can use filters to find large or old emails.
5. Next, enable AutoArchive & empty the Trash and Junk folders
6. Delete or save large attachments externally to free up space.

Cons: This method works only for emails, not for messages. 

Method 4: Reduce Mailbox Size by Compacting the PST File

If your Outlook Mailbox Size Not Reducing After Archiving, try compacting the PST file. Compacting your PST files will help reduce the mailbox size. 

1. Go to File >> Account Settings >> Data Files.
2. Select your Outlook file >> Settings >> Compact Now.

Cons: This method is not effective or unless you remove some space.

Additional Note: In case none of these methods work for you, you must try to recover your PST files to be able to reduce the Outlook Mailbox size. For that purpose only, you can use the Aryson PST Compress Tool. 

Method 5: Automated Way to Reduce Outlook Mailbox Size

The Aryson PST Compress Tool safely compresses large Outlook PST files to free up storage and improve Outlook’s performance. This helps the user to reduce Outlook PST File Size Without Splitting. Moreover, it allows users to perform bulk compression, remove attachments while saving them separately, eliminate duplicate emails, and apply a date filter on the emails for targeted compression.  The tool can split oversized PSTs and retain the original folder structure. And, it supports all Outlook versions from 2010 to 2021 on Windows 11, 10, 8, and 7. 

Note: In case the user wants to repair and restore a corrupt Outlook PST file, they can use the Outlook PST Recovery Tool. 

How to Compress PST Files to Reduce Mailbox Size

1. Download and open the PST Compress Tool on your computer.

2. Then, open the PST file you want to compress.

3. After that, select & preview the files displayed in the tree structure and hit Next.

4. Apply the additional features as per your requirement. 

5. Provide the desired file path to save the resultant file & start compression.

Conclusion

In short, to avoid mailbox full issue in Outlook, users must reduce their mailbox size. The user can do it by Deleting Unnecessary Data, Archiving Old Emails, using the Outlook Cleanup Tool, and compacting the Outlook PST file. But if none of these methods work for you, you’d better compress their files using the automated solution above.

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