'Initiate a connection with a mail exchange server.
This callback function runs after mail exchange server for the domain
has been looked up.
@type address: L{bytes}
@param address: The hostname of a mail exchange server.
@type port: L{int}
@param port: A port number.
@type factory: L{SMTPManagedRelayerFactory}
@param factory: A factory which can create a relayer for the mail
exchange server.'

def _cbExchange(self, address, port, factory):

    from twisted.internet import reactor
    reactor.connectTCP(address, port, factory)
