Outlook Data File has Reached the Maximum Size – Here’s the Fix

As you keep using Microsoft Outlook on your Windows computer, it makes these PST files store all your emails, attachments, and necessary stuff safely. As time goes by, these files can get big. When they get too big, Outlook might stop working and show you a message that says, ‘Outlook Data File Reached the Maximum Size.’ As a result, you won’t be able to use Outlook properly on your computer. But don’t worry! There are ways to fix it and make Outlook work smoothly again.

“Your mailbox has reached its maximum size limit at which you cannot send or receive more content. Empty your deleted item folder from Outlook or delete messages from your mailbox to create more space.”

Why Does the Error Message Occur?

The causes of the Outlook Data file xxx.ost has Reached Maximum Size because it will aid in resolving the issue. The Outlook file size limit issue occurs for several causes

• When the OST file is filled up to the threshold limit, it can not store any further data from the Outlook application. Therefore, Outlook will start showing the Outlook Data file has reached the maximum size issue.

• Another reason for this Outlook error message is corrupted OST files. When the OST file gets corrupted, you will not open the emails, or maybe the Outlook OST has reached maximum size.

The above are the reasons for the Outlook issue. Now, we will explain to you various methods through which you can resolve the error message.

Also Read: Outlook Mailbox Size Limit Exceeded

6 Solutions to Fix Outlook Data File Reaching Maximum Size

Here, we have various ways to resolve the Message Store has Reached its Maximum Size issue.

#1. Email Cleanup: Managing Your Inbox Efficiently

• First, open Outlook and click on the File button.
• After that, choose Info and then click on Cleanup tools next to Mailbox cleanup.
• Within cleanup tools, select Mailbox Cleanup.
• Then, click View Mailbox Size to see how much space your emails take up in the OST file.
• Use the Find button to search for older items. You can enter the number of days or file sizes for deletion, like finding and tossing out things you don’t need.
• At last, explore further options such as Empty Conflicts, View Deleted Items Size, and Find items larger than for more assistance in deleting unnecessary data and shrinking the OST file size. It does a detailed cleanup to make your Outlook work smoothly.

#2. Configuring Offline Data Settings for Outlook

The following approach will help you to resolve the OST has Reached the Maximum Size error.

• First, open your Outlook application on your local screen. Click the File button, then select Info.
• After that, choose Account Settings and click on it again from the info menu. Then, click on your profile icon and select Change.
• Now, look for the slider labeled Mail to keep offline in the settings.
• Use the slider to adjust the synchronization settings between 3 days to 5 years. As a result, it aids in controlling how much data gets saved offline.
• Move the slider to a lower value to synchronize less data. For example, if it’s set to 1 year, you can choose six months to reduce the OST file size.

#3. Adjusting Registry Keys for Outlook Optimization

Here’s another way to make your Outlook work better without deleting old emails – you can use some registry keys. You don’t have to say goodbye to your old emails to do this. By changing these settings, you can make more room for your Outlook files.

There are four settings you can adjust in the registry. Two of them, called “WarnLargeFileSize” and “MaxLargeFileSize,” work with a format called UNICODE. For Outlook 2010 and newer versions, these can go up to 50 GB. For older versions like 2003 and 2007, it’s 20 GB. Then there’s “MaxFileSize” and “WarnFileSize” that use ANSI format, and for Outlook 2000, these can go up to 2 GB.

For Outlook 2010, 2013, and 2016

Name	Type	Valid Data Range	Default
MaxLargeFileSize	REG_DWORD	0x00000001 – 0x0000C800	0x0000C800 51,200 (50 GB)
WarnLargeFileSize	REG_DWORD	0x00000000 – 0x0000BE00	0x0000BE00 48,640 (47.5 GB)
MaxFileSize	REG_DWORD	0x001F4400 – 0x7C004400	0x7BB04400 2,075,149,312 (1.933 GB)
WarnFileSize	REG_DWORD	0x00042400 – 0x7C004400	0x74404400 1,950,368,768 (1.816 GB)

For Outlook 2003 and 2007

Name	Type	Valid Data Range	Default
MaxLargeFileSize	REG_DWORD	0x00000001 – 0x0000C800	0x00005000 20,480 (20 GB)
WarnLargeFileSize	REG_DWORD	0x00000000 – 0x0000BE00	0x00004C00 19,456 (19 GB)
MaxFileSize	REG_DWORD	0x001F4400 – 0x7C004400	0x7BB04400 2,075,149,312 (1.933 GB)
WarnFileSize	REG_DWORD	0x00042400 – 0x7C004400	0x74404400 1,950,368,768 (1.816 GB)

#4. Reducing OST File Size by Compacting

Making your Outlook work faster is easy. One way to do this is by compacting your Outlook files to take up less space without losing anything important. Here’s how you can do it:

• First, go to your Outlook and click on the File button. Then, choose Account Settings and click on it again to move forward.
• After that, look for the Data Files tab among the options at the top. Find your OST file in this tab – that’s the one you want to make smaller.
• Then, click on the Settings option for that OST file. Now, choose Advanced to go to the advanced settings.
• In the advanced menu, find Outlook Data File Settings for compacting. Click Compact Now, then hit OK to confirm. That’s it! Your OST files are now smaller.

#5. Disabling Shared Folder Configuration

Okay, your Microsoft Outlook contains some ‘Shared Folders.’ These shared folders can make your Outlook stuff heavy! So, here’s a trick to make it lighter:

• First, open Outlook and click on File. Then, find Account Settings and click on it again. Lots of tabs will show up.
• After that, look for the Data Files tab. Choose the OST file you want to make smaller.
• Then, close that tab and go to Settings in Outlook. Click on Advanced and turn off Download Shared Folders.
• At last, restart Outlook and wait a bit. Now, your Outlook should be running smoother without carrying the extra weight of shared folders.

Here, we discussed the troubleshooting solution to resolve the Outlook Data File Reached the Maximum Size. You can check another approach also.

#6. Setting Up an Archive Folder in Outlook

• First, open your Microsoft Outlook account and find the File button at the top left corner.
• Click on Info and then select Cleanup tools.
• From the cleanup tools menu, find and click on Archive.
• In the archive window, pick the files or folders you want to move to the archive.
• Afterwards, specify where you want to save the archive folder by selecting the location in the browse box.
• Once everything is set, click OK to save the archived files to the chosen location.

If you’re still facing the error, your Outlook OST and PST files might be too large. If you want to split them, consider using the Cigati OST Splitter or Cigati PST Splitter. These tools will efficiently break down your bulky OST file into smaller sizes.

Final Words

There are numerous manual approaches to resolve the Outlook Data File Reached the Maximum size issue. However, these are not permanent solutions. They can fix the error temporarily. Make sure to choose the method where you feel more comfortable while accomplishing it.

You May Also Read: Outlook Error 0x80040115

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