An X.400 message transfer protocol for EMCON network situations

This paper describes P Mul, which is a new X.400 message transfer protocol. Compared with the conventional X.400 message transfer protocol P1 P Mul has two essential enhancements: it allows the integrated X.400 message transfer to destination message transfer agents (MTA), which are for a certain time under one-way communication (EMCON) condition and therefore not able to communicate with the source MTA. Secondly, as P Mul is based on the connectionless transport service and supports multicast communication techniques it can save a non-negligible amount of network resources. Additionally, this paper describes an implementation of P Mul within the X.400 system PP and reports the results of evaluation tests.