General
-------
This directory contains per-mailer channel (routing) tables from which
the <host>.chn file can be generated.

In general, these files have a list of domain names on the LHS and
the "host to send to" on the RHS, e.g:

	usc.ac.uk		vax1

which specifies that addresses of the form "user@usc.ac.uk" should
be send to the host "vax1"

However, the actual format of the channel tables depends on the mailer,
(see below) and is determined by the file name.

For example, any file whose name ends with "janet.chn" is assumed to be
a janet mailer channel table.


Channel Table Formats
---------------------
ether.chn  and  luucp.chn:
	These have the format described above; a domain name on the LHS
	and a hostname to send/relay to on the RHS.

uucp.chn:
	This has a slightly different RHS syntax which the same as that
	produced by pathalias(1), e.g.:

		usc.ac.uk		vax2!vax1!%s

	where %s is the user part of the address (converted to uucp form).

janet.chn:
	The LHS domain name is in big-endian form in this table.
	The RHS is a "hostname" to send to.
	If a janet channel table is specified, then by default
	all uk.ac.<name> domains are assumed to be routed to <name>.

bitnet.chn:
	This has the same format as the ether and luucp channel tables.
	If a bitnet channel table is specified, then by default all
	<name>.bitnet domains are routed to <name> (actual routing is done
	by the bitnet mailer).

top.chn:
	This has a domain name on the RHS, for example.:

		ac.uk			ukc.ac.uk

	which states that any address that ends in "ac.uk", which did not
	match a domain name in one of the mailer channel tables, is sent to
	ukc.ac.uk.


Examples
--------
The archive Examples.a contains sample mailer channel files.


How to make the <host>.chn file
-------------------------------
1. Create a mailer channel file for each mailer you have.
   This is best done by extracting sample channel files from Examples.a
   and editing them to contain the relevent data for this host.

2. Run "MAKE host file1 file2... " to create the <host>.chn file. 
   	e.g.   MAKE hwcs luucp.chn ukuucp.chn

   This shell script does a lot of work so be prepared to wait!


Supported Mailers
-----------------
MAKE looks for tables for the following mailers:

	ether.chn	(ethernet)
	luucp.chn	(local uucp)
	uucp.chn	(uucp)
	janet.chn	(janet)
	bitnet.chn	(bitnet)
	top.chn		(top level relaying)

If you have other mailers not listed here, then you will need to add
some code the the MAKE shell script. Good Luck!


Note
----
Make sure that the domains on the RHS of the relaying rules (in top.chn)
eventually match some domain on the LHS of a rule in one of the mailer
channel tables.
