Fixed Issue – Outlook is Sending Duplicate Emails

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  • Published on
    September 21st, 2021
  • Updated on
    February 16, 2022
  • Read Time
    6 minutes
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Summary:- This article is all about the reasons behind the user’s issue: “Outlook is sending duplicate emails” and how to troubleshoot them from happening again with the help of an expert solution.

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As usual, you will open your Outlook for answering the emails or talking with your natives. Suddenly saw that your inbox folders are full of duplicate emails: all having the same subject, similar Cc/Bcc, time stamp, and so on.

Reasons for Occuring Duplicates Emails in Outlook?

This condition, unfortunately, is not as rare as you expected. It can pause your searches since you have to search and examine the path of the duplicates, then find a resolve for it and lastly, clean up your mailbox. If you leave them alone, then at the end of the day, your mailbox is full of duplicate emails, and it will slow down the speed of Outlook.

Thus to help you out, we will discuss the top possible reasons for this Outlook sending multiple emails at once. Moreover, an automated solution that will securely fix Outlook is sending duplicate emails problem.

Reason 1: Received Emails is Corrupt/Damage

If you get an email on the server and it is corrupted, Moreover, due to that, it will generate duplicate emails while you begin the Send/Receive process of Outlook. To troubleshoot this, you will have to login into the email server and delete the corrupted emails or contact the IT Administrator to delete the damaged emails.

Reason 2: Synchronization of Outlook A/C On Multiple Devices

Your Outlook account is synchronized with multiple devices like desktop, laptop, tablet, and mobile. Hence, it will definitely generate several copies of duplicate emails. You can fix this only by deleting the duplicate emails one by one.

Reason 3: Due to Multiple Outlook Account

These days, Outlook users want to configure their personal and professional Outlook accounts together. In a specific email client, users have multiple accounts so their productivity may increase. But you have to remember to not use aliases of different ids on a single mailbox. If you do, then the specific mailbox may get led with similar Outlook emails.

Reason 4: Leave a Copy of the Messages on the Server

If you check the checkbox of Leave a copy of the messages on the server option. Then it will automatically create duplicate emails at each Send/Receive cycle. To fix it, Follow: Account Settings>>More Settings>>Advanced.

message on server

Reason 5: Users can Define Rules In Outlook that may Generate Duplicate

1 Rule: move messages from contact A to folder B

2 Rule: move messages that contain WORD in the subject line to folder C When you receive an email from contact A, it includes WORD in the subject line. Then you will get the same message in folders Y and Z also. To resolve this: with Microsoft Outlook sending multiple emails, you will have to change the setting of rules in Outlook.

Reason 6: Import PST File to Current Outlook Profile

Users Import/Export PST files from Outlook to send and receive emails in their accounts. In case you will export a PST file from an Outlook account and at the same time export it on the same account. Then it will generate duplicates of complete mailbox data items.

Reason 7: Send/Receive process is Still Running Stage

In case the Send/Receive process is in running stager and Outlook is not able to respond. Then the next sync will save the previous emails again. By deleting those emails manually, you will fix the duplicate mail issue.

Reason 8: On an IMAP Account

Users can set up an Outlook setting. So that it will automatically retrieve new emails, and in addition to that, if you start up and open the Inbox, you will see that each message is duplicate. To troubleshoot this, you will have to stop the setting Inbox startup.

Reason 9: While Forwarding Emails

When one can forward their Outlook account emails into another Outlook account, and in between the forwarding process gets stuck. Therefore, it will create loops, and the message will bounce back to the user account and create multiple duplicate emails. To overcome this Outlook is sending duplicate emails, changing the rule accordingly.

Reason 10: Subscribe Multiple Times a Mailing List

Duplicate Emails can also be created when one can subscribe multiple times to a specific mailing list. In this scenario, you will have to contact the person that will send you emails and inform them of this error.

An Expert Solution to Remove Duplicate Emails In Outlook

In the end, if you are still facing Outlook is sending duplicate emails in your folder, then opt with SysInfo Outlook Duplicate Remover and delete your duplicate emails of your Outlook PST completely.
The tool is efficiently developed to detect and delete the duplicate items of single and multiple Outlook PST without losing any data. In order to remove duplicate emails, it will use different comparison criteria like subject, StartDate, Body, EndDate, Companies Status, Cc, Bcc, Subject, etc.

Step By Step Guide To Remove Duplicate Emails in MS Outlook

  • Firstly, download and install the SysInfo Outlook Duplicate Remover.
  • Perform the installation steps and run the software as an administrator.
  • run software
  • Select the Single File or Multiple Files option to add the Outlook PST files.
  • choose file option
  • Check the folders from the tree and preview the mail and attachments if you want.
  • preview mail
  • Opt with Mail & Task Filter option to separate emails and tasks in between two dates.
  • choose filter
  • Select the different items like Mail, Calendars, Task, Contacts to remove duplicate items from them.
  • select duplicate item
  • Opt with Search Duplicate Items within the Folders or Search Duplicate Across PST file in which type you want to remove duplicate items from the chosen PST.
  • serach duplicate item
  • Click on the Specific Duplicate Criteria button and define the criteria for the comparison.
  • click on save
  • Select the Path To Save and locate the saving location for the new duplicate removed PST file.
  • choose path to save
  • Tap on the Convert button to initiate the deleting duplicate emails process.
  • tab on convert
  • In addition, you can also save the report of conversion.
  • save report


In this blog, you understand the different reasons why Outlook is sending duplicate emails. Therefore, to manage similar items and increase the performance of Outlook, you can go through with SysInfo Outlook Duplicate Remover Tool. It will check the duplicate items and remove them without any data hassle.

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