Resolve Outlook OST File Size Not Reducing After Archiving

Many Outlook users think that OST file size reduces after archiving but it does not always happen. You might archive a large number of messages and still notice that Outlook OST file size is not reduced after archiving at all. This can be frustrating especially if you are trying to free up storage or improve Outlook performance.

This issue is more common than it seems, and it is usually due to how Outlook manages OST files, how data synchronization works, or how compaction is managed correctly. In this blogpost, we will explain reasons and solutions to easily reduce the size of your outlook data file OST error.

Understanding OST Files

An OST file is a local copy of your mailbox data created by Microsoft Outlook. It allows you to store emails, calendars, contacts, and other data when you are not connected to the internet. Once you reconnect. Outlook syncs all changes with the server.

Key Characteristics of OST Files

• Used with Exchange, Outlook.com and IMAP Accounts
• Enable offline access to mailbox data
• Automatically sync changes when you’re online

OST files are specially useful in business environments where users rely on Microsoft Exchange or IMAP based servers. However, because they mirror the mailbox data they can grow quite large over time. When you archive old emails, you’re essentially moving them to a different location(usually a PST file). So, before this you must know the difference between OST and PST file. But unless Outlook compact OST file after move, its size might not reduce immediately, leading to confusion for many users.

Common Reasons Why OST File Size Doesn’t Reduce After Archiving

• If you deleted emails or moved emails into archives. Outlook makes that space available but doesn’t reduce OST file size.
• Archiving removes older items from the OST file and saves them in a PST file. However, the OST file remains in size unless you manually compact it and wait for Outlook’s background processes to do it.
• Outlook automatically compacts the OST file when you are not using your system and certain conditions are met like a significant amount of time.
• After archiving, Some emails or calendar entries with large attachments available in OST file. Additionally, hidden folders and system data like views or forms can consume storage without appearing in the mailbox.
• If Outlook fails to sync properly with the server, it might not fully clear or update the OST file. Sync errors or incomplete server communication can leave behind bloated data in the file.

Manual Methods to Fix Outlook OST File Size Not Reducing After Archiving

If your Outlook OST file size is not reduced after archiving, you can take several manual steps to shrink the file and improve performance. So, follow the procedure as we have stated below:

Method 1. Use Compact Feature

1. Open Control and Click on Mail(Microsoft Outlook).
2. Click on Mail and press on data files.
3. Select your OST files and click Settings and click on Advanced.
4. Browse Outlook data files and click on Compact Now.

Method 2. Use Mailbox Cleanup Tool

1. In Outlook, navigate to file and click on Tools.
2. Press Mailbox cleanup and use options like Mailbox size, older data, or larger files.
3. Delete or archive unnecessary data.

Method 3. Adjust the Mail to Keep Offline Slider

1. Go to File and click on Account Settings.
2. Press on Account Settings and select your email account.
3. Hit on Change and Adjust the Mail to keep offline.
4. Click Next and press finish to relaunch Outlook.

Method 4. Disable Shared Folder Synchronization

1. Go to File and click on Account Settings.
2. Press on Account Settings again and select your Exchange Account.
3. Hit on Change and More Settings.
4. Tap on Advanced and uncheck download folders.

Steps to Reduce OST File Size

1. First, download and launch automated software on your system.
2. Click on Convert Configured Outlook mailbox data or select from specific path.
3. Now, Select OST mailbox folders as you want to export.
4. Choose the PST file in the list of Saving options and choose Split PST file.
5. Use Advanced filter to export selective mailbox data.
6. Choose destination path and click on Convert to start fix Outlook OST file size not reducing after archiving.

Useful features of Recommended Software

• This software offers to convert OST to PST, PDF, EML, MBOX, and 25+ Export features.
• It offers an easy to perform interface to easily operate by any professionals or individual users.
• With this wizard, you can also use filter features such as date range, from, to, subject, exclude folders, organizer, root folder, exclude empty folders, mails, calendars, contacts and create exception log and many more.
• This software allows to restore and convert corrupted, orphan, dismounted, damaged, and inaccessible OST files.
• You can also import OST to Microsoft 365, Gmail, Yahoo, and all IMAP Supported email platforms.

Preventive Measures

• Deleted and junk emails take valuable storage in the OST file. Empty these folders regularly to keep your file size maintained.
• Setup auto-archive or perform manual archiving on a regular schedule of backup OST file. Moving old emails to a PST file reduces clutter and keeps the OST lean.
• Keep an eye on an OST file size through Outlook mailbox settings. If the OST file grows too large, use cleanup tools or compact it before problems arise.
• Train users to delete unnecessary emails, limit large attachments, and organize mailboxes properly. Small habits prevent major issues over time.

Popular Questions

Do archived emails still take up space in Outlook?

No, Archived emails are moved to a separate PST file and no longer take up space in the OST file. However, until you compact OST manually or wait for Outlook auto-compaction, the OST file may not reduce in size right away.

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How to fix Outlook OST reached maximum size?

To fix a full OST file, delete unwanted emails, empty deleted items, archive old messages to a PST file and use Outlook’s “Compact Now” feature. You can also reduce offline mail range or create a new profile to reset the OST file.

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How do I Reduce the size of the OST file in Outlook?

Delete unnecessary emails, archive old data to PST, empty deleted items and manually compact OST file via Account Settings and navigate to data files and hit on Settings and press on Compact Now. Here, Adjust sync settings to limit how much mail is available offline.

Overall Reflection

In this article, we have discussed the way to fix Outlook OST file size not reducing after archiving by manually and using advanced solutions. Manual solution takes lots of time and requires technical background to perform it correctly. While advanced solutions offer quicker results and require no technical background to perform it correctly.