PMDF System Manager's Guide

The returnenvelope keyword takes a single integer value, which is interpreted as a set of bit flags. Bit 0 (value = 1) controls whether or not return notifications generated by PMDF are written with a blank envelope address or with the address of the local postmaster. Setting the bit forces the use of the local postmaster address, clearing the bit forces the use of a blank addresses. Note that the use of a blank address is mandated by RFC 1123. However, some systems do not handle blank envelope from address properly and may require the use of this option.

Bit 1 (value = 2) controls whether or not PMDF replaces all blank envelope addresses with the address of the local postmaster. Again, this is used to accomodate incompliant systems that don't conform to RFC 821, RFC 822, or RFC 1123.

Note that the RETURN_ENVELOPE PMDF option can be used to set a PMDF system default for this sort of behavior.