Versions of PMDF prior to version 3.2 used the local channel to deliver messages across DECnet using VMS MAIL. While this can still be done, the use of channel DECnet MAIL-11 channels (d or d_ channels) is preferred for this operation. These channels are described more fully in Chapter 19; in particular, see Section 19.2
PMDF also includes two true DECnet channels, which use direct DECnet links to form a transport layer for PhoneNet or SMTP message transfers. DECnet channels are used to link multiple systems running PMDF that happen to be attached to the same DECnet. They are entirely distinct from DECnet MAIL-11 channels. The terminology is quite confusing and is due to the fact that DECnet is both a transport mechanism and mail system in its own right, yet the same name is used for both functions. This document always refers to DECnet's own message delivery system as DECnet MAIL-11 and to DECnet's transport mechanism as simply DECnet.
The automatic configuration generator generates a DECnet MAIL-11 channel if one is needed.