To enforce login policies on a per-server basis, the ALTER LOGIN POLICY has an optional clause, MULTIPLEX SERVER server-name.
The following statement creates a login policy called Reader1OnlyPolicy. By default, this policy prohibits access to servers:
CREATE LOGIN POLICY Reader1OnlyPolicy LOCKED=ON
This statement allows holders of Reader1OnlyPolicy to access only server Reader1:
ALTER LOGIN POLICY Reader1OnlyPolicy LOCKED=OFF MULTIPLEX SERVER Reader1
UserA is allowed to log in only on Reader1 and not on any other server in the multiplex:
ALTER USER UserA LOGIN POLICY Reader1OnlyPolicy