If you send an email to someone and get a bounce back error message from mailer-daemon@, the error message will provide you with the error type. The most common type of errors that we see for outbound emails are email errors 513, 550, and 553. Below is a brief description of what they are and what you can do to fix the error.
|CODE||WHAT IT MEANS||WHAT TO DO|
|513||Email address is misspelled or there is an error with authentication.||Double check your recipient email addresses and correct any mistakes. If everything's ok and the error persists, then it's caused by a configuration issue, please create a support ticket request at this point.|
|550||It usually defines a non-existent email address on the recipient side.||The great majority of 550 errors simply states that the recipient email address doesn't exist. You should contact the recipient by other means and correct the email address.|
|553||"Requested action not taken – Mailbox name invalid". This means that there is an incorrect email address in the recipients field.||Check all the addresses in the TO, CC and BCC field. There should be an error or a misspelling somewhere.|