Resolve Error Outlook Archive not Reducing Mailbox Size? Fix It

user Query: I use the Archive folder in Outlook to keep important old emails for future reference, but my mailbox is still showing as almost full or overloaded. Shouldn’t archiving reduce my mailbox size? I’m worried about losing data or breaking something if I try to fix this myself – is there a safe way to resolve this without risk?

Introduction
Firstly, learn about the reasons why the Outlook mailbox size is not reduced, even after archiving it. Further, you will be introduced to the advanced PST Splitter Tool and various manual approaches. To pick the best method to resolve this issue, you have to go through this blog thoroughly.

Why is Outlook Mailbox Size Not Reducing after Archive?

You might have archived your emails in Outlook to shrink your mailbox size. But the size hasn’t reduced due to the following reasons:

• When you archive, only old emails are moved, while new emails remain in your Outlook mailbox.
• You may have missed selecting certain folders, especially those containing large files, during the archiving process.
• Even if you’ve deleted emails, the Deleted Items folder still counts toward your mailbox size until it’s emptied.
• Your OST or PST file won’t reduce in size automatically—you need to manually compact it to reclaim space.
• If AutoArchive is not enabled, archiving won’t occur unless you run it manually.
• Outlook may take time to reflect changes, as mailbox size updates can be delayed.
• A corrupted or damaged Outlook profile can interfere with the archiving process or prevent accurate display of mailbox size.

Apart from this, there are various other reasons that lead to this issue. If you want to fix it, read this blog further. 

Resolve “Outlook Archive not Reducing Mailbox Size” Issue

You can use different methods to resolve this issue. Some of the effective ways are listed below, along with the detailed steps. So, read all of them and choose the solution that fits best. 

Tech 1. Restart Your Microsoft Outlook

Sometimes, caching makes it difficult to display the mailbox size updates. If you refresh and restart your Outlook application, the mailbox size might show accurately. Here are the steps to do this:  

1. First, close all tabs, including MS Outlook. 
2. Then, restart Outlook and move to Files and tap Tools. 
3. In the Tools, hit Mailbox Cleanup.
4. After that, click View Mailbox Size. 
5. Now, you can check all the details.

Tech 2. Compact Microsoft Outlook Data File 

If you archive or delete the emails or items, your mailbox size might be reduced. To do this, you need to compact the files manually. For this, follow the given steps:  

1. To start, visit the File and tap Account Settings in the Outlook application. 
2. Further, move to Account Settings and pick Outlook PST or OST data file under Data Files.
3. Next, hit Open File Location and close the Outlook tab. 
4. Thereafter, right-click on the PST or OST file in the File Explorer -> Properties.
5. At last, press the Advanced button -> click Compact Now to initiate the process.

Tech 3. Search Large Size Attachments Manually 

After archiving the emails, the mailbox is still full then it might be due to large-sized attachments. To deal with this, it is necessary to review and delete large attachments manually to free mailbox space. To complete it, read and follow the mentioned steps.

1. In Outlook, choose the folder to review. 
2. Later, navigate to View -> Arrange By  and then Size.
3. Then, look for large emails with attachments. 
4. After that, right-tap on the attachment -> Save As. 
5. Next, save the attachments locally. 
6. Afterwards, remove the emails without or along with attachments.

Limitation of all three Manual Methods

• Methods 1 and 2 only fix local Outlook/OST problems – they don’t touch the actual Exchange mailbox quota on the server. If your mailbox is full because the server-side quota limit is complete, then a restart or OST compact does not give any impact.
• Method 3 takes a lot of time when you have to go through this for several mailboxes or multiple users at once.
• If the problem spans across the organization or affects 10+ users, manual fixes just won’t hold up at that scale. At that point, it makes more sense to rely on an admin-level fix – like a retention policy, a PowerShell command to trigger the Managed Folder Assistant, or a third-party cleanup/migration tool.

Method 4. Expert Recommended Solution to Fix: Outlook Archive Does Not Reduce Mailbox Size

MacSonik PST Splitter Tool is a reliable utility to help in reducing the PST file size automatically. This wizard allows users to divide the PST file into smaller PST files, which makes it easier to keep and archive bulk data. Apart from this, it helps in resolving the Outlook archive not reducing mailbox size issues. Additionally, it is convenient for users with no technical expertise to split the large PST files instantly. In addition, it is known for completing with zero error and risk while maintaining the folder hierarchy throughout the process. 

Simple Steps to Outlook Mailbox Full After Archiving

Using the given instruction will help you reduce the PST file size by breaking it down. 

1. First, download and run the PST Splitter Software on your system. 
2. After that, tap Add File to browse and choose PST files to split. Hit Open and Next. 
3. Further, select the files and set the criteria to split the files accordingly. 
4. Then, hit Next and select the split options.
5. Next, assign the path to save it in your system. 
6. Lastly, click the Split to initiate the splitting process. 

Key Features:

• Helps divide single/multiple files 
• Helps handle duplicate emails from PST.
• It also provides a free demo version of the software.
• Represents the files in a tree structure.
• Embedded feature to apply a password.

Need more detailed instructions? You need to go through and read this guide, MacSonik PST Splitter, and take help from it.

Conclusion 

Here, this blog provides all the necessary information that might be needed to fix Outlook archive not reducing mailbox size issues. It includes the different situations that let the issue occur and manual techniques to fix it. Other than this, an automated software for splitting multiple PST files at once. Additionally, the split PST files will be easier to archive. As a result, the mailbox size will be reduced automatically. 

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