This article is from the Jobs FAQ, by Snoopy snoopy-at-sopwith.uucp.
Three pieces of information belong in the Subject: line.
In order: the location, a brief job description, and the hiring
organization. The location and job description are required,
the hiring organization may be left out of the Subject: line
by third party recruiters, or to make room for a better
Subject: COUNTRY-STATE/PROVINCE-City Job_Description Company
Subject: US-IL-Chicago Foobar Developer, Acme Widget Inc
Subject: US-NY-NYC Foobar Developer, Acme Widget Inc
Subject: US-DC-Washington Foobar Developer, Acme Widget Inc
Subject: DE-Munich Foobar Developer, Acme Widget Ag
Subject: UK-London Foobar Developer, Acme Widget Ltd
Subject: offsite Foobar Developer, Acme Widget
Use, in order, the country code, state or province code (if applicable),
and the city. Do not leave out the country code. If the country is
US or CA, then do not leave out the state/province code. (The state/
province code is optional for countries other than US and CA.) Do not
leave out the city. Use the dash ('-') character to separate the
portions of the location. Use one or more blank space characters (' ')
between the location and the job description, and between the job
description and the company. In order to allow computerized searches,
it is important that everyone use the same standardized syntax shown
above. Do not invent your own unique format.
If the job is in a small town or suburb near a larger, better known,
city, you may choose to use the larger city in the Subject line.
(Providing that the larger city is not in a different country, state,
or province than the smaller city.) If there is enough room on the
Subject line, you may choose to include both the large city and the
suburb on the Subject line by thinking of the suburb as a further
division of the metropolition area. For example:
Subject: US-IL-Chicago-Lisle Foobar Developer, Acme Widget Inc
The same idea can be used to include some other subdivision of a
Subject: US-NY-NYC-Midtown Foobar Developer, Acme Widget Inc
The standard format shown above allows both humans and the computer
to tell whether, for example, "CA" means "California" or "Canada":
Subject: CA- means Canada
Subject: US-CA- means California
...and to distinguish between cities with the same name:
If you need to know what the country code for a particular
country is, I have included a list of them in section Q-19.
Section Q-20 contains a list of US state codes and
Canadian province codes.
See also section Q-3.6.
The job description is not currently standardized, although there
has been some discussion of this in misc.jobs.misc.
Note that most newsposting software will provide the string
"Subject: " for you. If you actually type "Subject: US-GA-At..."
your posting will look like:
Subject: Subject: US-GA-Atlanta Peach Pickers ...
...which is not what you want.