Simple "mail" thinks I'm at localhost.localdomain

From: Ed Skinner (Ed_at_REMOVETHIS.flat5.net)
Date: 09/02/04 

Date: Thu, 02 Sep 2004 10:39:50 -0700

     Using simple "mail" in a script, it says I am
"edski@localhost.localdomain" (and the relaying system is rejecting the
message) even though all other facets of the networking software appear to
be properly configured. I wrote a couple of quickies and verified that
gethostname(2) and so forth are all returning the configured values, not
"localhost.localdomain".
     One final clue: I can use "nail" (not "mail") with a "-r
user@host.com" (using the correct values) and get the relay system to
accept and forward the message.
     Anyone know where "mail" gets the host's name and domain? ("nail"
will do the same if I omit the "-r user@host.com" option.)
     Thanks!