email @webserver auto-forwarders

What is the email address that does not end with an extension (.com, etc)? Examples: statindustry@webserver bransonsurreyinn@webserver The reason I ask is that I use SMTP2GO for SMTP support since the Google Cloud Platform we use as a VPS blocks ports used by SMTP. SMTP2GO says, "We've noticed some additional auto-forwarders. These include the below invalid addresses: statindustry@webserver bransonsurreyinn@webserver Please can you also disable these auto-forwarders?" What are these address and how can auto-forward be disabled for them?