> easily change my mail user agent and (less easily) LISTSERV to expand
> +/-nn with 2 zeroes, but what about MAILER, NETSERV, SMTP, etc?
 
I just tried the experiment of modifying the zone code (with STCP) from
"EDT" to "-04" for a few seconds while I sent a piece of mail.  Mailer
performed as advertised: it added a Received line marked "-0400".  SMTP,
however, seems to take note of the zone code only when it starts up, and
it just went on using "EDT" during the test.  One of these days, I'll
get a chance to shut down SMTP and start it up again with the zone code
set to "-04".  NETSERV, I would say, doesn't matter, since it uses IBM
NOTE and therefore isn't strictly legal anyway.
                                    John