How to Increase Mailbox Size in Outlook 2003, 2007, 2010, 2013 and 2016

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Microsoft Outlook is the most widely used email client application by not only the Windows users but by Mac OS users as well. However, the Windows users use Outlook more than the Mac users. Most of the users who are using Windows OS are more likely to use the MS Outlook application to communicate and send and receive email messages. If the user has been using Outlook since a long time, then he must be aware of the PST file size limitations problem. The users want to resolve the issue of how to increase mailbox size in Outlook. The issue with the PST file size has become a frustrating situation for every user. The limitation with the PST file size is not the same, it actually varies from version to version. In this blog, we will help you with a solution to fix Outlook mailbox size not updating issues.

Need to Increase PST File Size Outlook 2016, 2013, 2010, 2007, 2003

Nowadays, many of the users are widely using the latest version of MS Outlook. It means the users are using Unicode PST file format. The file format itself provides a lot of space, but sometimes users may face some issues with the file size limitations. If the Outlook mailbox size increases to the maximum file size limit, then it may cause some serious problems to the users. Users might face system crashes or any severe data loss. At times, the situation of corruption of the Outlook PST file also occurs. The corrupted or damaged PST file can easily be repaired using the smart recovery tool for Outlook.

We will now move further and see the process to increase Outlook mailbox size without any hassle.

How to Increase Mailbox Size in Outlook Manually?

We will be discussing the most effective trick here which doesn’t require any third party utility to increase storage capacity of PST for Outlook. Follow the below provided steps.

Step 1: Open Registry Editor

Press Win+R, type Regedit and click on the enter button.

Open Registry Editor

Step 2: Modify PST Mailbox size

You will see a tree like structure under the computer tab in the left pane. Click on the HKEY_CURRENT_USER directory.

Modify PST Mailbox size

Now, according to your Outlook version, go to the following registry path.

For Single Users

Outlook 2003: HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\PST
Outlook 2007: HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\PST
Outlook 2010: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\PST
Outlook 2013: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\PST
Outlook 2016: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\PST

For Administrators

Outlook 2003: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Outlook\PST
Outlook 2003: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Outlook\PST
Outlook 2007: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\PST
Outlook 2010: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\14.0\Outlook\PST
Outlook 2013: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\PST
Outlook 2016: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST

Step 3: You can now see the PST entry in the structure. Double click on it.

Step 4: If you are unable to find the below two entries in the right pane, then you need to create the values manually to fix how to increase mailbox size in Outlook.

  • MaxLargeFileSize
  • WarnLargeFileSize


Step 5: Right-click on the blank space to create MaxLargeFileSize. Click on New and choose DWORD (32-bit) value.

pst step

Step 6: Type MaxLargeFileSize as its name.


Step 7: Now, right-click on the blank space to create WarnLargeFileSize. Select New > DWORD (32-bit) value.


Both these two values are available in the registry. Now, you need to define their data value.

Step 8: Double-click on the MaxLargeFileSize and define its value and the base type to provide a solution to how to increase mailbox size in Outlook.


Note: Make sure the value you will enter would be in MB and should be larger than the maximum file size of the Outlook PST file.

Choose decimal in the base type and click on the OK button.

Step 9: Double-click on the WarnLargeFileSize and define its value.

Step 10: Now, close the Registry Editor.

After following the above manual trick, users can easily resolve the issue to extend outlook storage space to resolve the query on how to Increase Outlook Mailbox Size.

Wrapping Up

Above in this blog, we have discussed the perfect and recommended solution to fix how to increase mailbox size in Outlook problems. The oversized PST file can cause trouble to users and users might face the situation of corruption. If the PST files got corrupted due to the over size, then you can easily restore all the data from the corrupt file using the recovery tool for Outlook as mentioned in the above blog.

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