Techniques for secure federation of data communications networks are provided. The techniques employ an edge proxy server to route messages depending on a federation mode. In Direct federation mode, an edge proxy server of a network is configured to exchange messages with a specified set of entities, such as other networks, servers, other devices, or users. In Automatic federation mode, an edge proxy server may accept all incoming messages from entities that have a valid certificate. In Clearinghouse federation mode, the edge proxy server forwards all outgoing messages to a specified, trusted clearinghouse server.