/SUBSTITUTE_DOMAIN=[NO]NAME=fully-qualified-domain

    Optional.

    By default, the From: and Return-Path fields display the
    sender's name and fully qualified domain. NONAME causes the
    sender's domain name to be omitted from the Return-Path field.
    If you specify a fully qualified domain name (/SUBSTITUTE_
    DOMAIN=NAME=fully-qualified-domain), that specified domain name
    is displayed as the sender's domain name.

    For example, suppose you specify the fully qualified
    domain name eagle for the sender's return path
    (/SUBSTITUTE_DOMAIN=NAME=eagle). When user magpie on host
    condor.hawk.eagle.org sends mail to daw on another host,
    user daw sees the return path as magpie@eagle rather than
    magpie@condor.hawk.eagle.org.

    This is what daw sees:

        #707        18-NOV-2002 14:02:02.71                  MAIL
    From:   SMTP%"magpie@eagle"
    To:     SMTP%"daw@crow.ravin.rook.org"
    CC:
    Subj:   Big sale today!

                                   NOTE

       For changes made with the /SUBSTITUTE_DOMAIN qualifier
       to take effect, you must stop and restart SMTP. For more
       information about stopping and starting SMTP, refer to the
       HP TCP/IP Services for OpenVMS Management manual.