Presently, DECnet channels are only supported on OpenVMS and Tru64 UNIX systems.
PMDF includes an SMTP over DECnet channel which uses the standard SMTP protocol to convey messages, over DECnet as a transport agent. On OpenVMS, PMDF also includes two additional types of channels which use DECnet as a transport agent. That is, these three types of channels are:
Note that the terminology used here is a bit confusing. This is brought about from the fact that DECnet is both a transport system and a mail system. SMTP over DECnet channels, or alternatively on OpenVMS, PhoneNet over DECnet channels, are used to link multiple systems running PMDF that happen to be attached to the same DECnet. They are entirely distinct from the DECnet MAIL-11 channels. This document always refers to DECnet's own message delivery system as DECnet MAIL-11 and to DECnet's transport mechanism as simply DECnet.