1. Check to make sure you have not clicked the ‘Send’ button twice or more before the message was fully sent.

2. Make sure the email is not set with an automatic reply or forwarding feature.

3. Check if the ‘CC’ or ‘BCC’ field contains more than 1 of your email address.

4. Check if the email was sent to a mailing list or distribution list.

5. Check for external forwarding rules outside of your current email application. This could be on a webmail service, or a plugin or other software that you have installed on your computer.