How to Fix “Outlook PST File Has Reached its Maximum Size” Error? Solved

What Exactly Happens Next? When you encounter the error “Outlook PST file has reached its maximum size”, you won’t be able to send or receive any more emails. This can be a head-scratching situation for all MS Outlook users.

But don’t worry. In this write-up, you will find the complete information and step-by-step guide to resolve the “PST has reached the maximum size” or “OST file has reached maximum size” errors using both manual methods and expert solutions.

The Outlook Data Files PST vs OST, we all know that Outlook creates OST and PST files to store their data including email, contacts, calendars, notes, journals, etc. Outlook creates two types of PST files in Outlook ANSI and UNICODE. On the other hand, an OST file is a replica of the synchronized mailbox, which can used in offline mode.

Now it is important to know Why the Outlook Data File Has Reached its Maximum Size. It happens when we send or receive emails, a copy of your email data including attachments has been saved locally. And because of that, your Outlook data file size grows with time, which may potentially result in slowing down your computer and Outlook’s performance.

To resolve the issue of Outlook PST File has Reached its Maximum Size, including problems with OST files, first, we have to understand the Outlook data files’ maximum size limits:

• Outlook 97 and 2002 have a 2 GB size limit (ANSI PST)
• Outlook 2003, and 2007 size limit is 20 GB
• All the latest versions of Outlook including the 2021 size limit are 50 GB and from Outlook 2003 to Outlook 2021 all versions create UNICODE PST files.

Before starting, let’s have a quick view on what you will get to know in this article through the Table of Contents.

Fix “Outlook PST File has Reached its Maximum Size” Easily

Splitting your data files is one of the methods to solve the “PST and OST has reached the maximum size” error. To know more about it, you can directly check the professional solution:

• Step 1: Start the given solution and click the Next icon
• Step 2: Add the Outlook data automatically or manually.
• Step 3: Enable “Use Recovery Mode” for corrupted files.
• Step 4: Check the box of required folders/subfolders.
• Step 5: Browse the location to save the resultant data.
• Step 6: Apply the Advanced Filter Option for more features.
• Step 7: Lastly, hit the Split button to start the process.

#1: By Compacting your Data Files

Compacting your data files is another effective method to fix the “PST has reached the maximum size” error. Steps:

1. Head to the File tab in Outlook.
2. Go to Account Settings >> Account Settings….

   

3. From the Data Files tab, choose the needed data file.

   

4. Hit on the Settings >> Advanced and then Outlook Data File Setting.

   

5. Choose Compact Now, and select the OK button.

   

And your OST data file successfully compacts now.

#2: Delete Unnecessary Emails

1. Firstly, open your Outlook account.
2. Choose the needed emails to delete.
3. Hit on the Delete icon to remove them.

#3: Fix “Outlook PST File has Reached its Maximum Size”: Cleanup Tool

After removing all the unnecessary emails, you must clean them from the “Deleted Folder”, which is another reason for the increased PST file size in Outlook for flawless performance. Here are the steps:

In Outlook 2013, 2016, 2019 and 2021

1. Click on the File >> Info >> Cleanup Tool and hit the Empty Deleted Items Folder option.
2. A confirmation message will appear and hit the Yes button.
3. Lastly, your deleted folder will empty successfully.

For Outlook 2010 and 2007

1. Right-click on the Deleted Items >> Empty Folder option to remove deleted emails.

#4: By Archiving Emails & Data

1. Go to File >> Info >> Tools >> Clean up old items in Outlook.

   

2. Choose the option “Archive this Folder and All Subfolders”.
3. Select the Mail folder and put a date from the “Archive Items Older Than the field”.
4. After that, choose to Include items with the “Do not AutoArchive”.

   

5. Press on the OK icon.
6. Now repeat the same process to break the data file based on different date ranges.
7. Or you can enable the Auto Archive option by clicking on it.

#5: Solve “OST File Reached Maximum Size” with a Registry Key

This is another way to resolve the “Outlook data file has reached the maximum size” error by modifying the MaxFileSize, WarnFileSize, MaxLargeFileSize, and WarnLargeFileSize registry entries to extend the PST file size limit. In case if you don’t want to delete your emails and attachments.

1. Firstly, Open “run” and search Registry.

   

2. Open the PST folder by following the mentioned path above.
   

   Important Note: MaxFileSize, WarnFileSize, MaxLargeFileSize, and WarnLargeFileSize registry entries are not created, then right-click on the space, and select the DWORD (32-bit) value.

   

3. Then, enter the registry entry name as MaxFileSize and double-click on it.

   

4. And type the value in the “Value Data Field” box, for example – 1GB=1024*1024*1024 byte.

   

5. Hit the OK button and repeat the same process to create and enter the value for respective entries WarnFileSize, MaxLargeFileSize, and WarnLargeFileSize.

And finally, your “Outlook PST File has Reached its Maximum Size” error is resolved, but always remember that there are some points that you have to keep in your mind:

Important Note: It is not necessary that after increasing the size of the PST file, your all problems will be solved. Increasing the PST file size will make your file inaccessible, corrupt, and damaged, which may cause loss of your data. So, trust this method completely.

Now let’s talk about how you can resolve the “OST has reached the maximum size” error, by the following given methods.

#6: By Splitting Your OST File

Your “Outlook data file reached the maximum size” error can be resolved by dividing your OST file into smaller parts. This method involves exporting connected OST files into PST format using the Import/Export tool. All the steps are given below in detail:

1. Firstly, launch your Microsoft Outlook.
2. Head to the File tab, and choose Open & Export >> Import/Export.

   

3. Select the Export to a File option.

   

4. After that, select “Outlook Data File (.pst)”

   

5. Choose the needed mail folders >> Next icon.

   

6. Then, set the required destination path as per your choice.

   

7. Enable the filters according to your needs.
8. Lastly, click on the Finish icon.

Your OST file will be saved in .pst format at the selected location. If this method also does not work, then jump to another way.

#7: Rebuild your Outlook Data Files

If your OST file is not responding and becomes inaccessible due to its large size, then recreate it by following the steps:

1. Start Control Panel in Outlook.
2. Choose Mail >> a box will open “Mail (Microsoft Outlook)”.
3. After that, hit on the “Data Files” tab.
4. Select the linked Outlook data file and hit Open File Location.
5. Rename your file with the .bak suffix, and it will make a backup copy of your OST file.
6. Lastly, restart your Outlook and it will automatically create a new file and sync with it.

#8: Disable Shared Folder Sync to Fix “Outlook PST Has Reached its Maximum Size”

1. Go to the File tab then Account Settings >> Account Settings….
2. Choose the OST file from the Data Files tab.
3. Select the Settings and then Advanced >> Outlook Data Settings…
4. After that, disable the “Download Shared Folders” and OK icon to continue.
5. Finally, start your Outlook again and wait for the synchronization process to complete.

If still things are not working for you, then please read another method.

#9: Optimize Offline Data: Adjust Mail to Keep Offline

1. Again, open Outlook, and go to the File tab.
2. Choose Info >> Account Settings >> Account Settings from the appearing options.
3. After that, choose the email account/Profile and hit on the Change icon.
4. Lastly, set up the “Mail to Keep Offline” folder as per your wish.

Customize your Outlook synchronization settings by selecting a timeframe: 3 years, 5 years, or ‘All.’ The choice you make determines how far back Outlook will retrieve and sync your emails. However, if you opt for a shorter timeframe, you might miss older emails.

Time to Say Goodbye

Here we have explained the complete information and step-by-step guide to resolve the “Outlook PST file has reached its maximum size” error by using manual methods and expert solutions. Manual methods are straightforward including emptying deleted folders, archiving emails, and using Registry. However all methods have some limits and risks. And, if you have a corrupted and damaged PST file and your Outlook is not working then you should go for the expert tool. The software comes with amazing features and filters, which makes the software more usable for all users.