Outlook 2016 Sending Emails Twice – Reasons & Solutions

admin | February 26th, 2019 | outlook

The duplicity of email messages while sending mails via Microsoft Outlook is one of the most annoying issues. Microsoft Outlook 2016 sending emails twice or more than that. It is equally problematic for users, who have one or more web/ desktop based accounts. The reason behind this is numerous copies of mails get received in the Inbox of the receiver. On the other hand, multiple copies of emails get stored in Sent Items folders or Outbox folder of the sender. These duplicate emails in the mailbox are very bothersome. As we know, Outlook is a popular platform for the exchange of information therefore; such functioning of MS Outlook cannot be acceptable. There might be several reasons for what Outlook sending multiple copies of emails with attachments as mentioned in the below part.

Why Outlook 2016 Sending Emails Twice?

The major factors that may cause Outlook to send multiple copies of a single message are the following:

  • Sluggish Connection to Mail Host: The POP and IMAP both Outlook account works with the server timeouts. This is used to inform Microsoft Outlook to think about a lost connection if there is no response from the server. At the slow internet connection, it can arrive at the timeout and will submit the messages once again when the send or receive process will begin for the next time. The duplicates are generated when the server received the messages. However, the message of acknowledgment was not received before timeout. Therefore it results in MS Outlook 2016 sending emails twice and thus duplicates are generated.
  • Short Time for Send/Receive Connection: At times, send or receive interval is put to a very short time. And this result in the emergence of Outlook sending emails twice issue. After uploading an email message to the server, it is possible that the next cycle of send or receive will begin before the completion of the first send or receive process.
  • Installation of Anti-Virus in System: Microsoft Outlook sending emails multiple times, can occur due to the installation of anti-virus software in the system. Some anti-virus programs conflict with Microsoft Outlook due to which application starts sending multiple copies of emails each time. These duplicate emails consume the same space as the original email message.

How to Stop Outlook 2016 Sending Emails Twice?

In order to resolve the issue of Outlook sending multiple copies of emails with attachments, follow the methods discussed below:

Method 1: Increase Server Timeout

For POP and IMAP account, the default server timeout is 1 minute. Therefore, it is recommended to increase it to 2 to 3 minutes.

Note: Do not put the time for more than 3 minutes.

  1. To increase the server timeout, perform the steps given below:
  2. Click on File option and choose Account Settings
  3. Now, hit a double click on IMAP/POP3 account
  4. In the next dialog box, you need to click on More Settings
  5. Select Advanced Tab in the Change Account box
  6. Finally, move the slider in the section of Server Timeout to increase the time and click OK

Method 2. Increase the Send or Receive Time

To fix Outlook 2016 sending emails twice, follow the steps to increase the send-receive time. To check the interval of Send/Receive of emails, you need to open Send/Receive Settings and view the current tasks.

  • For Outlook 2007 and Prior Versions
  1. You need to click on Tools and choose Send/Receive
  2. Now, click on Send/Receive Settings and then Show Progress
  • For Outlook 2010 and Later Versions
  1. Choose the tab of Send/Receive from the ribbon
  2. After this, choose Show Progress

Now, in case you are seeing more than two tasks in the box, this implies that the Send/Receive interval is very short. To change this follow the instruction given below:

  • Firstly, choose the downward arrow next to Send/Receive Groups
  • Now, select Define Send/Receive Groups from the drop-down menu
  • Finally, in setting the time section click on Schedule an automatic send/receive every…

Note: Always set the time greater than 5 minutes. If you have various accounts, set it more than 10 minutes.

Method 3. Disable Anti-Virus Program

Outlook 2016 sending emails twice or sending multiple copies of emails along with attachments issue is valid if you have installed an anti-virus in your computer. You need to disable it just for a short period and then attempt to send the message from Outlook. If no duplicates are created, this means that anti-virus is the cause of the issue. You need to uninstall it in such a situation.


Due to Outlook’s immense popularity, even some small issues may create hurdle in between the work of users. One such problem a user may encounter when Outlook sending multiple copies of emails. Therefore, considering the importance of MS Outlook, we have discussed the reasons behind this Outlook 2016 sending emails twice or multiple times issue along with simple troubleshooting techniques. There are cases when MS Outlook 2007 sending the same email multiple times issues occurs in the user account. If you are an Outlook user, regardless of its version, this blog will help you resolve the issue.