When a server administrator registers a public XMPP service with, we verify the registration by sending email to the the hostmaster/postmaster/webmaster email addresses for the root domain. (By "root domain" we mean the lowest-level domain that can be looked up in whois — e.g., if the XMPP service is running at then we contact the owners and admins for We also check the server's test results on and visit the website of the service to make sure that it is accurate, provides contact information, etc.