Outlook is Sending Multiple Copies of an Email [Resolved]

Written By Deepmala
Chirag Arora
Approved By Chirag Arora  
Published On September 27th, 2023
Reading Time 5 Minutes Reading

Duplicity of email is one of the most irritating problems Outlook is sending multiple copies of an email, both for the senders who send email through Outlook as well as recipients holding different web based or desktop based accounts.

This is because multiple copies of email get received in the Inbox of the recipients account(s) whereas several email copies get stored in Sent Items folder or sometimes in Outbox folder as well, though they are sent only once, causing huge problems. Duplicate emails in the receiver’s Inbox and multiple copies of email in either the Sent Items folder and/or Outbox of Outlook is really an annoying situation.

Such an abnormal functioning of Outlook mail program is certainly not acceptable and definitely occurs due to some irregularities caused due to one or several reasons. This article discusses the most common configuration issues that lead to formation of duplicate copies of email and methods for prevention as well as cleanup of the already created numerous copies.

Outlook Is Sending Multiple Copies of an Email – Cause & Solution

‘Outlook is sending multiple copies of an email’, though not a usual or common complaint in Outlook, it happens sometimes or the other during the usage of the widely used desktop mail client. Moreover, it generally happens with email having attachments. But it does not have with each mail having an attachment file. The cause of this problem might be because of the following reasons:

1. Cause: Virus Scanner Integrated with Outlook

When a virus scanner that integrates itself with Outlook, is installed on the machine the problem of email duplicity mostly occurs. This is because the scanner scans the outgoing emails as well. It has been found that the installed virus scanners in any windows machine cause more of similar issues than they assist in making things easier.

Resolution: Disabling Virus Scanner Integration

It is therefore recommended to disable the virus scanner integration with Outlook, completely. The reason being, disabling does not cause any problem and Outlook gives an even better performance than when it is used with enabled virus scanner integration. There does exist multiple ways to disable the virus scanner integration.

2. Cause: Short Time Interval B/w Send & Receive

The problem of multiple copies of emails being sent, though sent only once, also occurs due to setup of short time interval between the send and receive task of emails. This is because when the send/receive time gap is set to a short duration, say below 5 min; and the mail takes a while to upload onto the mail server, it happens that the next send/receive process already starts before the previous one gets over.

This causes an accumulation of Send/Receive process that is yet to be over and requires to be finished. In the nastiest times, it happens that the message still stored in the Outbox get submitted again for sending. In this way, multiple duplicate copies get sent and received.

How to Solve the Outlook is Sending Multiple Copies of an Email Issue

To prevent and resolve such an issue the Send/Receive Progress dialog can be opened to check if there exists any backlog or also the Send/Receive time gap can be increased in the following way.

Increase Send/Receive Time Interval, Let Backlogs Get Over

  • To Check for Backlogs
    • In Outlook 2007 and below versions:
      • Click on ‘Tools’ tab go to Send/Receive, then Send/Receive Settings and finally Show Progress
      • In Outlook version 2010 and 2013
        • In tab ‘View’ click on button, Show Progress
  • To Change Send/Receive Time Gap
    • In Outlook 2007 and older releases
      • First click on ‘Tools’ tab and then on Options button.
      • In the Options window, click on Mail Setup tab and then Send/Receive where time interval can be changed.
    • In Outlook edition 2010 and 2013
      • Go in the sequence: File > Options > Advanced > Send/Receive for altering time gap.

Note – The time interval should be set more than 5 minutes. However, when there are 3 or more accounts configured, it should not be less than 10 minutes.

Cause: Slow Connection to Mail Host

In some cases, the problem ‘Outlook sending multiple copies of an email’ is also caused when Outlook users work with a slow connection to the mail host. This is because both IMAP and POP3 accounts function with server timeouts.

This actually tells Outlook when to consider a connection as lost, if no response is received from the server after a fixed amount of time, which by default is 1 minute.

When on a slow or unreliable connection it is highly possible that server gets timed out and in such situations, Outlook re-submits the Outbox email message in the next Send/Receive time period, thus creating duplicate emails.

Also Read: Not Receiving Some Expected Emails

Resolution: Increase Mail Server Time-out

When this is the source behind multiple ‘sent email’ copies being created, the solution could be extending the mail server time-out i.e. increasing Internet speed. And this can get possible by resetting the internetworking devices such as modem, router(s), hub, Access Point, etc. or by contacting the Internet Service Provider. Increasing the mail server timeout to 2-3 minutes generally resolves the issue.

Moreover, defining it more than 3 minutes is not at all suggested, as it means that the actual issue is something else and not the slow connection.