Remove Duplicate Emails On Microsoft Exchange Server Mailbox

Remove Duplicate Emails On Exchange Server Mailbox with Powershell script. Or use An Automated solution to Extract Mailboxes and remove Exchange duplicates.

Remove Duplicate Emails On Microsoft Exchange Server Mailbox

Possible Ways to Remove Duplicate Emails On Exchange Server Mailbox

Exchange Servers are a favorite of enterprises and most businesses. The reason being, it’s functioning and expenditure perfectly suits the budget of a large scale as well as a mid-sized business. However, one would only be willing to make investments if the desired output is also achieved. Data duplication is a common scenario as far as large storages are concerned, and Exchange is no exception. The database consists of a multitude of mailboxes, which increases the quantity of data it stores. Thus, the process to remove duplicate emails on Exchange Server is a challenge owing to the size of database and number of items it stores in the form of multiple mailboxes.

The following blog not only targets a solution but also shares it in a variety of both, manual workarounds and commercial utilities. You can find out about both in order to choose which the most suitable approach is.

Grounds for Duplicate Item Generation

Exchange Server is a well-managed and administered platform, which is delicately monitored by an administrator. Therefore, the chances of its mailbox surfacing issues that demand a solution should actually be less but is relatively high.

Content duplication is an issue that tends to surface usually because of implementation of rules on a particular mailbox. On the other hand, there is a set of other server specific reasons in Exchange like:

  1. Synchronization: There are times when the synchronization of the server with client mailbox is not successful due to technical glitches like interrupted network connection or incorrect credentials. This sometimes results in repeated synchronization of the mailbox contents causing item duplication.
  2. PST Import: Exchange Server can import an Outlook Data File into its mailbox. However, the problem occurs when while importing the PST file you forget to deselect the checkbox for – not importing duplicates.

PowerShell Script to Remove Duplicate Emails On Exchange Server Mailbox

With Exchange, PowerShell removes duplicate emails using the script. Remove-DuplicateItems.ps1 is the script that you can run on PowerShell in the presence of EWS. The script allows you to either clear off the duplicate items detected in the specified storage or store them separately in the Deleted Items folder.

The default script offers to add mailbox name or folder name to be scanned for duplicates. This could either be an email folder, appointments, or address book folder. Thus, you can remove duplicates from any of the mentioned categories. However, the syntax will only be able to scan one mailbox/folder a time along with some other limitations, which are discussed below.


  1. Running the script requires understanding the parameters in order to modify them according to your requirements.
  2. You can only process one mailbox/folder at a time while removing duplicates using the provided script. In order to remove duplicates for multiple folders, you need to merge them together.
  3. The script runs on either the entire mailbox or a specified folder. Thus, multiple folders (excluding unwanted) cannot be scanned for removing duplicates.

Automated Commercial Solution: to Remove Duplicate Emails From Exchange

Discussed above is a tried and tested measure to remove duplicate emails on Exchange Server with the means of PowerShell script. However, if you are being refrained by the corresponding limitations, the recommendation is that you go for a third party application instead.

Here is a combination of software applications that will render you duplicate removal in the most convenient forms.

Extract Mailboxes: To start to remove duplicate emails on Exchange Server multiple mailboxes, you need to first extract them as a PST format file. Download and Install, Exchange EDB to PST converter.

  1. Run the software to reach the home screen where you have to click Add File and browse the desired EDB file.
  2. A preview of the mailboxes with their contents will be generated on screen. Click on Export to begin.
  3. Choose PST as the preferred output type. Select the mailboxes to be converted with folders that are to be included. Click on Browse to specify a destination path and click on Export to extract the mailboxes selected.

NOTE: The software is capable of processing Exchange database and mailboxes even if the storage is corrupt or in an orphan/dismounted mode.

Eliminate Duplicates: Extracted mailboxes need to be separated into individual storage’s to remove duplicate emails on Exchange Server. Download and Install the Outlook duplicates remover tool.

    • When you run the software, the following window will appear on your screen. Click on Add File(s) or Add Folder to browse and select the converted mailboxes as PST.

Remove Duplicate Emails

  • Define the categories to be scanned for duplicates and choose a mode of duplicates removal:
  • Within Folder(s) applies to the removal of duplicates found within a particular folder.
  • Across Folder(s) checks for duplicates across all the available folders, if available.

Click on Browse to specify a destination path for saving the output.

  • Click on Remove Duplicate emails to start with the process of extracting mailbox contents without duplicates.

This is the only possible method to remove duplicate emails from Exchange mailbox in multiples. Other than this, no other method, for instance, the PowerShell script can render you a way to remove duplicates from multiple mailboxes.

Final Word

Exchange server is the most preferred collaboration platform in a large number of organizations for its suitability to all levels of businesses. However, it is as problematic too as preferable it is. This is common with just any email server because of the regular load of data exchange it handles. Moreover, the management of excessive data also demands excessive administration, which if not provided may result in performance issues. One such situation is where the manageability of the mailboxes goes out of hand and results in data duplication due to reasons like improper import, synchronization issues, or so on. When a situation like this encounters users are compelled to remove duplicate emails from Exchange Server as part of the solution. However, it is the method used for this purpose that matters and not the results because that remains constant. Implementing manual workarounds is already a thing of inconvenience and is not recommended. Moreover, the use of third party commercial tools is a convenient help for the way it demands no user input and guarantees an instant output generation too. Thus, the latter is recommendable over the former for evident reasons.