sunos 4.0.1, $m in sendmail.cf

[Guy Harris]

>What should sendmail be setting it to?  The yp domainname, or the internet
>domainname?

"sendmail" sets it from the YP domainname.  It does so *after* it reads in
the configuration file, so you can't override it in the configuration
file, alas.  The rules it appears to use are:

	1) do a "getomainname" call;

	2) if the first character of the result is "+", replace it with
	   ".";

	3) Search for the first "." in the result:

	   4a) if it's found, set "$m" to the part of the string that
	       follows the first ".", and set the class "m" to the same
	       thing;

	   4b) if it's not found, leave "$m" and the class "m" alone.