Microsoft Outlook email client uses PST file format to store mailbox data items such emails, contacts, calendars, notes, etc. There are basically two types of PST file, which varies from version to version. ANSI type PST file is created by Microsoft Outlook 2002 and all below version having 2 GB file size limit. On the other hand, UNICODE type PST file is created by Microsoft Outlook 2003 and above version with 20 GB file size limit. In Microsoft Outlook 2013 and above version it is extended to 50 GB. Read to know how to fix Outlook data file has reached the maximum size Outlook 2016, 2013, 2010, 2007.

Sometimes, despite of this large storage space, the size of PST file exceeds its maximum limit. However, if PST file exceeds its maximum file size limit, then it starts creating an issue like corruption, slows down the performance of Outlook, etc. Now, to retain the normal functioning of Microsoft Outlook, it becomes important to troubleshoot the Outlook data file has reached the maximum size 2016.

For Quick Solution: Download SysTools PST Splitter Software to Split Large Outlook PST Files into Smaller Parts.

From past few days, whenever I launch Microsoft Outlook 2016 on my machine it displays an error stating Outlook data file has reached the maximum size 2016. Initially, I always ignore the message and continue working normally. But from yesterday, this error has stuck on my MS Outlook window and I am unable to remove it at any cost. I do not know how to troubleshoot this problem? If anyone knows any solution, please suggest.

How to Fix Outlook Data File Has Reached the Maximum Size 2016 Issue?

Whenever Microsoft Outlook data file reaches its maximum size limit, it displays a warning message for the same. It means that PST file has not reached the upper limit of the maximum size. So, still, there is a hope that a user can expand the size of PST file. A user can do this manually by modifying the registry entries of Outlook. The size limit of PST file is defined by the two registries discussed below:

The MaxFileSize registry entry: It determines the total limit at which extent the Microsoft Outlook PST file can grow. As the limit reached, Outlook will not allow users to add any more data. In MS Outlook 2016/ 13/ 10, it is 50 GB.

The WarnFileSize registry entry: It defines the maximum storage capacity of PST file. When the Outlook data file reaches the maximum size limit, PST file is not allowed to add more data. But unlike MaxFileSize registry, one can increase the size of PST file by changing the entries in the registry. In MS Outlook 2016, it is 47.5 GB, which is further expandable to 50 GB.

How to Edit Registry Settings to Increase the Limit of Outlook Mailbox Size?

Now, to change the WarnFileSize registry entry in order to expand the Outlook data file size limit, follow the steps mentioned below:

  1. To begin the process, click on the Start >> Run
  2. After that, type regedit in the Open box and click on the OK button
  3. Now, you need to expand My Computer option from the left pane. Then expand HKEY_CURRENT_USER
  4. Next, you need to expand Software >> Policies
  5. Then, expand Microsoft >> Office
    After that, based on the versions, expand:
    11.0 for MS Outlook
    12.0 for MS Outlook 2007
    14.0 for MS Outlook 2010
    15.0 for MS Outlook 2013
    16.0 for MS Outlook 2016
  6. Then, simply expand Microsoft Outlook
  7. Now, you need to click on the PST file and in the right pane, right-click on the MaxLargeFileSize
  8. Here, you have to click on the Modify button and enter the value in the Value data box
  9. At last, click on the OK button
  10. In the same, a user can change the value in WarnLargeFileSize data also. You just need to right-click on it WarnLargeFileSize and follow steps from 8 to 10.

In this way, a user can easily troubleshoot the Outlook data file has reached the maximum size 2016 message. After doing all this, the maximum size limit of PST file is increased and it becomes accessible in Outlook again.

Also Read: How to Merge Multiple Outlook PST files into one in Outlook 2016?

How to Reduce the Size of PST Files Manually?

Now, to avoid this Outlook data file has reached the maximum size 2016 error message, it is suggested to reduce the size of PST file. This section of the blog will discuss various solutions for the same.

Manual #1: Delete All Unwanted Data Items

To free up some of the storage space in the PST file, a user is suggested to delete the data that is no longer required. This will help in overcoming the large size PST file issues and keep archive data in an organized manner. Now, to do the same, follow the steps mentioned below:

  1. To start the process, open PST file
  2. After that, choose the data items that are no longer required by you
  3. Now, simply Delete of all them
  4. Then, empty the Deleted Items Folder and erase them permanently.

Manual #2: Archive the Outlook PST File

One can archive PST file data items also and delete them from the original PST file. To archive PST file, follow the steps given below to troubleshoot Outlook data file has reached maximum size:

  1. To start the process, open MS Outlook and go to File menu
  2. Then, click on the Clean up Tools >> Archive option
  3. After that, mention the date to choose the PST files that you want to archive and click on OK button
  4. After performing all these steps, Microsoft Outlook moves all selected messages to the archive data file. A user can access these messages from Archives folder in Outlook.

Alternative Approach to Reduce Outlook PST File Size

It might be possible that above discussed manual approaches fail to provide satisfactory results. Thus, to have a guaranteed solution, a user is advised to use a professional tool named as SysTools PST Splitter. It is designed specially to split large size PST file into multiple parts. This application lets users divide PST file in four different ways, i.e., by date, by size, by folder, and by year. A user can choose any of them based on their requirements to fix outlook data file has reached the maximum size.

outlook data file has reached the maximum size

Also Read: How to Export Mac Outlook OLM to Outlook PST without losing any data?


As the number of emails in mailbox increases every day, the size of PST file is also increasing. When it exceeds the predefined size limit it starts creating issues. Thus, keeping this need of users in mind, different methods to troubleshoot the Outlook data file has reached maximum size 2016 are covered in this blog. A user can simply refer them and get rid off such type of error messages quickly.