PMDF Programmer's Reference Manual

The envelope "From:" address for a message to be sent should be specified with the PMDF_USER item code. With this item code, only a user name can be specified; PMDF_send will automatically append the official local host name to the name so as to produce a valid address.

The PMDF_ENV_FROM item can be used to specify an envelope "From:" address which is not a local address. This is usually not necessary: applications which enqueue non-local mail should probably be using the API routines rather than callable send.

If neither PMDF_USER or PMDF_ENV_FROM are specified, then the user name associated with the current process will be used for the envelope "From:" address. When PMDF_USER is used, the "From:" header line address will be derived from the envelope "From:" address; when PMDF_ENV_FROM is used, the "From:" header line will be derived from the user name of the current process. ² Only privileged users can specify with PMDF_USER a user name different than that of the current process's. On OpenVMS systems, WORLD privilege as a default privilege is required. On UNIX systems, the process must have the same (real) UID as either the root or pmdf account. On NT systems, PMDF_send can only be used by privileged accounts such as Administrator.