Outlook Duplicate Remover – Remove Outlook Duplicates from PST

Outlook data file, commonly known as PST or personal storage table, has a size limitation problem which can cause severe problems, i.e. from slow Outlook performance to corruption. An oversize PST file is always prone to corruption. Also, it can slow down your Outlook client, and cause other performance and functioning issues. Having duplicate emails in Outlook is the key reason for increasing PST file size. Duplicate emails and other mailbox content need more space in the file, and it results in increasing PST file size. Whenever an Outlook data file is reached to its maximum size limit, i.e. 2 GB for ANSI PST and 20-50 GB for Unicode PST, the Outlook client starts working abnormally. This will cause tremendous performance degradation and other issues. The situation becomes much worse than before when the PST file size goes beyond its limit. This can cause corruption in your mailbox, and you can lose all your emails and other mailbox content.

You might be interested in How to Repair PST File with scanpst.exe?

Now the question is how to overcome this situation. If you’re having duplicate items in your Outlook PST files, you must remove them in order to make your PST files handy and immune to corruption. In this post, I’ll show you an easy manual trick to remove Outlook duplicates from PST files. Before we can discuss on Outlook duplicate removal, you should know what Outlook duplicate items are and why they occur in your Outlook mailbox.

Outlook Duplicate Items

In MS Outlook email client, duplicate items can be anything like email message, contact, calendar, entry, task, note as well as attachment. A duplicate item needs exactly the same size what the original mailbox item does, i.e. if the size of an email message is 100 KB, this means the duplicate email message has also the same size. Do you know why duplicate items occur in Outlook mailbox? Have you ever tried to find out the reason behind this? There’re numerous reasons which can cause duplicate items in Outlook, such as:

  • Receiving multiple copies of an email message again and again from any recipient. In these days, companies or organizations send same email messages, press releasesnewsletters, etc. regularly for business promotions and awareness. This may create duplicate items in Outlook mailbox.
  • During synchronization process, an interruption can also cause duplicate items in Outlook data files. Or if the synchronization process is executed incorrectly, duplicate items can be occurred in your mailbox.
  • Make sure that the Leave Messages on the Server option is not activated. If it’s activated, disable it in order to avoid duplicate items.
  • Make sure the configuration of Outlook rules is correctly executed, otherwise you may face duplication in your Outlook mailbox content. Also, make sure the Move a copy to rule is applied only a single time to a particular email message.
  • Sometimes duplicate items can be occurred during PST merging process if it is not correctly performed.

Due to all these reasons (discussed above), duplicate items can be occurred in Outlook mailbox and cause oversized PST file. Now the question is how to remove Outlook duplicates from PST mailbox. Generally, there’re two ways to do this: an easy manual trick and a professional solution. First we’ll talk about the manual trick that doesn’t require any third-party tool.

Manual Outlook Duplicate Remover

The manual trick to remove Outlook duplicates is so easy and safe to perform. Just follow the steps shown below to know how to remove Outlook duplicates:

Step 1: Launch Microsoft Outlook client on your system. Now select the folder from which you want to remove the duplicate items.

Step 2: On the View tab, click Change View option.

Step 3: Now change the folder view to table type view.

Note: Click Manage Views... check the view mode which you're currently on, i.e. either folder view or table view.

Step 4: On the Manage All Views window, check the view type.

Note: Use the following combinations of views and fields:

Calendar with appointments; contacts with phone list; inbox with messages; journal with entry list; and notes with notes list.

Step 5: Now right-click the column heading, and then click Field Chooser in the options.

Step 6: At the top of Field Chooser, select a field from the list.

Step 7: Now drag down the Modified field to the table heading.

Step 8: The duplicate items you want to remove must have a unique date from the original set of items. Therefore, click the modified heading to sort the items by this field.

Step 9: Now select the items you want to remove. And finally, hit Delete button to delete the selected items permanently.

Professional Solution – Remove Outlook Duplicates

Another way to remove Outlook duplicates is a professional solution, known as Outlook Duplicate Remover Tool. Software has been smartly designed to provide excellent results in a very quick time. Manual trick can take your enough time, but professional tool is swift and quick in action. It can safely remove Outlook duplicates from PST mailbox in order to make the Outlook data files handy and immune to corruption. PST files of any size or any format, i.e. be it ANSI or Unicode, are exclusively supported by this software. Before using this software, make sure the PST files from which you want to remove Outlook duplicates, are neither corrupted nor password-protected.

Remove Outlook DuplicatesFrom PST


Outlook Duplicate Remover software is available with free demo version. I personally recommend users to evaluate the software before purchasing the licensed version. Generally demo version of a commercialware tool works exactly same as the licensed version does. Demo version of this software allows users to remove duplicate items from first 25 email items of each mailbox folder of each selected PST file.

PST Duplicate Remover Demo

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