Overview
Duplicate emails are most often caused by a POP3 email client re-downloading the same message or by multiple addresses forwarding to one address. This article covers these common causes and how to prevent duplicate emails.
Confirming an email is a duplicate
You can confirm if an email is a duplicate by reviewing the headers of the message. If it's a duplicate, you will see the same Message-Id value in the different emails:
"Message-Id: <46007331.1050908@example.com>"
Which email settings cause duplicate emails?
Review each of the following sections as these are most often the cause of receiving duplicate emails.
Does a corrupted POP3 profile cause duplicate emails?
The most common cause using the POP3 protocol in your email client. The POP3 protocol is known to download the same message in the following situations:
- If you have enabled the option "leave a copy on the server".
- If you're accessing the same email account on multiple computers.
Unfortunately, there's not much you can do to eliminate duplicate messages unless you change the way you access that particular email account.
If you do not have a specific reason to use a POP connection, it's highly recommended you update it to an IMAP connection instead. View the POP3 vs IMAP article for further details.
Do forwarding addresses cause duplicate emails?
Another common cause is if you have configured multiple addresses to forward to one address. If so, your email client will view them as new email messages.
Review your domain's email settings in the panel to ensure you have not created multiple forward addresses.