Mysql problem is solved with giving localhost. But the mail Question was if add a domain on one server with a centralized(name as vpopmail)database. it can be accessible on other server from same database.
For example i add one domain on Testmail server and add one user. These all information stored in mysql vpopmail database.
Now on other server where vpopmail is also installed with mysql support running on other abover defined server.So Can i accesss/authenticate all user of Server 1 on this second server.