To get the first message to a pseudonymous recipient, we need a SURB Server
 which can dispense SURBs for various identities. This is like a nymserver
 but does not have to handle the actual message traffic, so it requires a lot
 less storage and bandwidth. The agent can maintain the SURB supply just like
 it would with a human sender. The SURB Server can be instructed to require a
 ticket from potential senders to limit DoS attacks, and that requirement can
 be published in the ID Record.

 I'm still working out the protocols for this, but basically the SURB Server
 would be just another type of Transport Record, one that effectively says
 "go ask this server for a transport record". The important point is that the
 agent is in a perfect position to keep everybody stocked with a reasonable
 number of SURBs.