When sending an email and you receive the error
"The account or domain may not exist; they may be blacklisted, or missing the proper DNS entries."
You will want to make sure that the domain name's routing is correctly set in the user's cPanel -> Email Routing.
If the user's domain name's MX record is resolving to the server, it should be set to "local" if the domain name's is resolving to a remote server it should be set to "remote." You can also choose "automatic."
More details about email routing on our website here: