The F=D delivery agent
flag is used by sendmail.cf header commands to
force the inclusion of date information:
H?D?Re-sent-Date: $a
H?D?Date: $a
The F=D delivery agent flag has no special
internal meaning to sendmail. It is a convention
that is used only in the assorted Date: header
definitions (Date:). See F= for a general description of this process.
