{"id":4956,"date":"2026-02-28T09:55:29","date_gmt":"2026-02-28T09:55:29","guid":{"rendered":"https:\/\/www.softaken.com\/guide\/?p=4956"},"modified":"2026-02-28T09:55:29","modified_gmt":"2026-02-28T09:55:29","slug":"why-are-there-two-ost-files-in-outlook","status":"publish","type":"post","link":"https:\/\/www.softaken.com\/guide\/why-are-there-two-ost-files-in-outlook\/","title":{"rendered":"Why Are There Two OST Files in Outlook? Causes and Fixes"},"content":{"rendered":"<p><strong>Overview<br \/>\n<\/strong><span style=\"font-size: 1rem;\">Every time you open your Outlook data folder and notice two OST files for the same account. That can create profile confusion, increased disk space usage, sync conflicts, slower performance, and potential mailbox data mismatch.<br \/>\n<\/span><span style=\"font-size: 1rem;\">And you might be wondering:<\/span><\/p>\n<ul>\n<li>Why did this happen?<\/li>\n<li>Is it safe to delete one?<\/li>\n<li>Will I lose emails?<\/li>\n<li>How do I properly fix it?<br \/>\nIf yes, then this guide explains the causes, safe fixes, and professional software to resolve issues with two OST files in Outlook, especially when corruption or orphaned files are involved.<br \/>\nAlso read: <a href=\"https:\/\/www.softaken.com\/guide\/fix-ost-file-corruption-in-outlook\/\">Tips to Avoid OST File Corruption in Outlook<\/a><\/li>\n<\/ul>\n<h2>Why Does Outlook Create Two OST Files?<\/h2>\n<p>The OST \u2013 Offline Storage Table file is created when you configure a Microsoft 365, Exchange, or IMAP account in MS Outlook. It stores a synchronized offline copy of your mailbox.<br \/>\n<span style=\"font-size: 1rem;\">Below, I have mentioned certain situations that cause two OST files in Outlook for the same account-<\/span><\/p>\n<h3>Outlook Creating Multiple OST Files &#8211; Common Causes<\/h3>\n<p>Here are some of the most common reasons for multiple or two OST files in Outlook-<\/p>\n<p><strong>Recreating Your Outlook Profile<br \/>\n<\/strong><span style=\"font-size: 1rem;\">When you delete or set up your Outlook profile again, it creates a new OST file. In addition, the old file usually stays in the folder, which is why Outlook keeps creating new OST files.<\/span><\/p>\n<p><strong>Mailbox Moved to a New Server<br \/>\n<\/strong><span style=\"font-size: 1rem;\">If you migrate your Mailbox to a new Exchange or Microsoft 365 server, Outlook generates a new file during the sync process.<\/span><\/p>\n<p><strong>Changed Windows User Profile<br \/>\n<\/strong><span style=\"font-size: 1rem;\">As Outlook can\u2019t connect to the old OST file, and when you recreate or reset your Windows user profile, it automatically creates a new file.<\/span><\/p>\n<p><strong>Corrupted OST File<br \/>\n<\/strong><span style=\"font-size: 1rem;\">If MS Outlook detects corruption or sync errors in the existing OST file, it stops using it and creates a fresh file to fix the issue.<\/span><\/p>\n<p><strong>Network or Connection Problems<br \/>\n<\/strong><span style=\"font-size: 1rem;\">A temporary server, AutoDiscover, or internet connectivity issue can interrupt proper validation. Which can lead to Outlook creating multiple OST files.<\/span><\/p>\n<h2>Is It Safe to Delete the Duplicate OST Files?<\/h2>\n<p>It\u2019s the most common question of users that deleting the files can lead to data loss.<\/p>\n<p>But you don\u2019t have to worry about it. Since \u2013<\/p>\n<p><strong>Yes, <\/strong>you can delete your OST file, but only if you\u2019re sure which one is active.<\/p>\n<p>Since OST files are cached copies of your mailbox stored on the Exchange Server:<\/p>\n<ul>\n<li>If your mailbox is syncing properly, deleting an inactive OST file is usually safe.<\/li>\n<li>Outlook will recreate it if needed.<\/li>\n<\/ul>\n<p>However, removing the wrong file can cause data loss if:<\/p>\n<ul>\n<li>If it\u2019s an orphaned OST file.<\/li>\n<li>Exchange account is no longer accessible.<\/li>\n<li>Files contain unsynchronized data.<\/li>\n<\/ul>\n<p>In such cases, before deletion, a professional recovery method is recommended.<\/p>\n<h2>How to Fix Duplicate OST Files in Outlook<\/h2>\n<p>You can try fixing it in multiple ways, but here I\u2019ll explain mainly two solutions. The Manual method and the Professional method, so that you can choose wisely.<\/p>\n<h3>Manual Method to Resolve Duplicate OST Files in Outlook<\/h3>\n<p>With technical knowledge or guidance, you can manually delete or rename duplicate files for this problem. However, I\u2019ll recommend that you rename the files instead of deleting them, as it will be safer.<\/p>\n<p><strong>Step1: Identify the Active OST File.<\/strong><\/p>\n<ul>\n<li>First, go to MS Outlook<\/li>\n<li>Then click File&gt;Account Settings&gt;Account Settings<\/li>\n<li>Next, tab on Data Files<\/li>\n<li>Check the file path of the active file<\/li>\n<\/ul>\n<p><strong>Step2: Close Outlook Completely via Task Manager.<\/strong><\/p>\n<p><strong>Step3: Find the OST folder in the default location.<\/strong><\/p>\n<p><strong>Step4: Rename the Outlook OST file instead of deleting it.<\/strong><\/p>\n<ul>\n<li>Compare the file and rename the suspected duplicate file<\/li>\n<li>Restart Outlook<\/li>\n<li>If everything works fine, you can safely delete it later<\/li>\n<\/ul>\n<h4>Why Manual Deletion is Not Safe?<\/h4>\n<p>Here are several reasons that you must know why the manual method is not reliable:<\/p>\n<ul>\n<li>It <strong>doesn\u2019t display any preview before deletion<\/strong> to verify important mailbox data beforehand.<\/li>\n<li><strong>Risk of unsynchronized data loss<\/strong> as your unsynced email or drafts can be lost permanently after accidental removal.<\/li>\n<li><strong>Orphaned OST files become unrecoverable <\/strong>once deleted without recovery software<\/li>\n<li><strong>Active file deletion risk, <\/strong>as similar file names can cause accidental removal.<\/li>\n<li><strong>No backup creation option, <\/strong>as these methods don\u2019t generate a secure backup before removing the OST file.<\/li>\n<\/ul>\n<h3>Professional Method to Securely Fix Two OST Files in Outlook<\/h3>\n<p>When you\u2019re unsure which files contain important data or which one is corrupted, rather than deleting anything, you should convert OST data to PST for data backup. You can delete the duplicate files later once the conversion is done. <span style=\"font-size: 1rem;\">For swift and reliable conversion, you can use <\/span><strong style=\"font-size: 1rem;\">Softaken <a href=\"https:\/\/www.softaken.com\/ost-to-pst-converter\">OST to PST Converter<\/a><\/strong><span style=\"font-size: 1rem;\"> that comes with a user-friendly GUI and offers multiple advanced features.<\/span><\/p>\n<p style=\"text-align: center;\"><a class=\"maxbutton-1 maxbutton maxbutton-download-now\" target=\"_blank\" rel=\"nofollow noopener\" href=\"https:\/\/www.softaken.com\/dls\/ostfileexporterdemo.exe\"><span class='mb-text'>Download Now<\/span><\/a>\u00a0 \u00a0 <a class=\"maxbutton-2 maxbutton maxbutton-buy-now\" target=\"_blank\" rel=\"nofollow noopener\" href=\"https:\/\/www.softaken.com\/buy-ost-file-exporter\"><span class='mb-text'>Buy Now<\/span><\/a><\/p>\n<h4>Here are Some Advanced Features that Make it an Ideal Solution to Use.-<\/h4>\n<ul>\n<li>Compatible with both the latest and older versions of Outlook and Windows.<\/li>\n<li>Handle batches and bulk of files with no file size restrictions.<\/li>\n<li>Filters emails by data, sender, subject, or recipient.<\/li>\n<li>Fully standalone utility and doesn\u2019t require other applications.<\/li>\n<li>Support password-protecting Outlook OST files.<\/li>\n<li>Maintains email stricter, hierarchy, attachments, and data integrity.<\/li>\n<li>Automatically skips folders that are empty.<\/li>\n<li>Offers file and folder mode-specific conversion.<\/li>\n<li>Avails Free Demo of the tool with 24\/7 customer support.<\/li>\n<\/ul>\n<h4>\u00a0Follow these Easy and Simple Steps to Run this Tool-<\/h4>\n<ol>\n<li>First, <strong>download and launch<\/strong> the utility on your computer.<\/li>\n<li>Next, <strong>Browse and Add<\/strong> <strong>OST<\/strong> file of any size.<\/li>\n<li>Then, examine the preview of the uploaded file on <strong>preview pane<\/strong>.<\/li>\n<li>Now select <strong>PST as the output format<\/strong> and <strong>Browse<\/strong> destination path.<\/li>\n<li>Lastly, click the <strong>Convert Now Button <\/strong>and it\u2019s completed.<\/li>\n<\/ol>\n<h2><strong>Conclusion<br \/>\n<\/strong><\/h2>\n<p>Two OST files in Outlook are a common issue caused by profile changes, server migration, or file corruption. This can cause confusion to the users, and removing or renaming it is important to solve this.<\/p>\n<p>Therefore, here in this blog, I have explained Manual and Professional methods. As, proper identification, backup, and conversion allow you to fix duplicates without losing emails or mailbox integrity.<\/p>\n<p>However, manual deletion is risky, time-consuming, and complex. In contrast, a professional solution like this ensures data safety, is quick and easy to use.<\/p>\n<p>In addition, you can try its <strong>Free Demo<\/strong> and examine its features before investing in the paid license version.<strong><br \/>\n<\/strong><\/p>\n<h4><strong>FAQs<\/strong><\/h4>\n<p><strong>Q1. Why do I have Two OST files with the Same Exact Size?<\/strong><\/p>\n<p>This happens when Outlook creates a new OST file after profile reset, server, migration, or a corruption issue. If both files were fully synchronized with the mailbox before the change, they can appear the same size even though only one is currently active.<\/p>\n<p><strong>Q2. Can I Delete One of the OST files in Outlook?<\/strong><\/p>\n<p>Yes, but only after confirming the active files. As OST files are just cached copies of your mailbox stored on the server. If your account is syncing properly, deleting the inactive file is generally safer because Outlook can recreate it. However, you should never delete it if the account is no longer accessible or if the files contain unsynced data.<\/p>\n<p><strong>Q3. How can I Identify the Active OST file in Outlook?<\/strong><\/p>\n<p>You should first Open Outlook, then go to Files&gt;Account Settings&gt;Account Settings&gt;Data Files. The file marked as default is the active OST file. You can also check its file path to match it with the files stored in your system folder.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview Every time you open your Outlook data folder and notice two OST files for the same account. That can create profile confusion, increased disk space usage, sync conflicts, slower performance, and potential mailbox data mismatch. And you might be wondering: Why did this happen? Is it safe to delete one? Will I lose emails? [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":4958,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_sl_quick_summary":"","_sl_featured":"","_sl_entry_faq_json":"","footnotes":""},"categories":[26,40],"tags":[],"class_list":["post-4956","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-ost-file-exporter"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Why Are There Two OST Files in Outlook | Reasons &amp; Fixes<\/title>\n<meta name=\"description\" content=\"Discover why are there two OST files in Outlook, the common reason behind the multiple OST files. 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