why am i sending mutt mail with my FQDN??

[Gary Kline]

The problem with t rying to use mutt, even when I reach my mailserver on 
aristotle.thought.org, is that *somehow* -- I do not understand how -- but 
for some reason, mutt tacks on the FDQN rather than simply my domain name.
I was using Giorgos' $MAIL env variable; now that I switched to Baptiste's 
longer method:: same thing.  mutt still prepends the hostname.

The following I sent to myself,

From: Gary Kline <kline at tao.thought.org>
Subject:   testing
To: Gary Kline <kline at magnesium.net>, kline at thought.org

it never reached me at magnesium.net.  Can anybody  clue me in?
-- 
Gary Kline  kline at thought.org   www.thought.org  Public Service Unix
    http://jottings.thought.org   http://transfinite.thought.org