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How To Fix Outlook Sending Duplicate Emails? 

If Outlook keeps sending the same email twice, thrice, or more number of times, it will become a huge issue like outlook sending duplicate emails. Unless you fix it immediately.

Note: The problem usually occurs in the case of emails with attachments.

You might want to know the reasons why Outlook is functioning in this bizarre way.

The following are some causes for your outlook sending duplicate emails:

  • Your virus scanner might be the cause.
  • The internet speed, while sending or receiving emails, could be very low.
  • There might be an issue with your router or modem.

How to fix the issue?

Now, continue reading this page to find out how to solve the “sending of duplicate emails” problem in Outlook:

Disabling or Uninstalling your Anti-virus:

  • Try disabling the antivirus software on your system just for a few minutes.
  • Now, send an email from Outlook. Check if more than one copy of the same email has been sent.
  • In case no duplicate emails have been sent from Outlook, it indicates that the antivirus on your system is the actual cause of the entire issue.
  • However, disabling the Antivirus every time you send emails is not a permanent solution.
  • We need to look for ways to fix the problem caused by your Antivirus.

Increasing the Server Timeout:

When you use IMAP or POP to configure or set up your emails, you will have to concentrate on your server timeout. The server timeout, by default, would have been set to 1 minute. To resolve your issue, you need to increase the server timeout to 2 or 3 minutes. But, please avoid setting this value to more than 3.

The following are some detailed steps to alter your server timeout:

  • If you are using Outlook 7 or an older version, navigate to the Tools tab.
  • Then, select the Account Settings option.
  • In case you are using Outlook 10 or a more recent version, then go to File and then choose the Account Settings option.
  • Now, double-click the IMAP or POP3 account (whatever you are using for your email configuration).
  • You will see that the configuration dialog box appears on your screen.
  • In this dialog box, select the More Settings option.
  • Now, the Internet E-mail Settings window will be displayed. In this window, click the Advanced tab.
  • Go to the Server Timeouts section. Here, you can see that the default value is 1 minute.
  • Now, drag the slider that is provided between the Short and Long options. Drag it such that you increase the server timeout value to 2 or 3. As mentioned before, do not set it to more than 3.
  • Finally, you have to click the OK button at the bottom of your Internet E-mail Settings window.
  • After you have finished the above steps, try sending emails from Outlook again to see if the problem outlook sending duplicate emails is persist.

If the issue persists, decrease the email send/receive time on Outlook.

  • Go to the Send/Receive tab and click Show Progress. If you see more than two tasks running, you should increase the time interval.
  • To do so, go to Tools and select the Send/Receive settings option under the Send/Receive tab.
  • Now, click the Define Send/Receive Group option.
  • In the dialog that opens, increase the default value beside the ‘Schedule an automatic send/receive every: ‘option.
  • Outlook will no longer send duplicates of your emails.
  • We have now seen how to prevent from outlook sending duplicate emails.
outlook sending duplicate emails