Best Way To Fix SMTP Error 550 Unknown User

If you are experiencing the SMTP 550 unknown user error, the following user guide will help you.

The sender will receive an inflatable return message ‘550 5.1. 1 Unknown user” when the recipient’s mail server cannot find the recipient’s delivery account there. Sometimes a single typo in an email address with a recipient can cause this email delivery error. A missing alphabet and possibly a wrong character can lead to confusion in an email address.

Ben Olden