When I wrote,
| > [W]ouldn't $LOGNAME(_at_)$HOST work just as well and be more flexible?
Era Eriksson responded,
| (HOST doesn't contain a FQDN, at least not here. I'd love for a
| portable method to get a host's FQDN.)
It is fully qualified on every machine where I've ever run procmail, so I
didn't know that it might possibly not be. I've occasionally written recipes
that depend on its being fully qualified.
But still, the raw machine name should be enough information for Harry's
X-Delivered-Via: header.