Where is $MAIL set? (login process)

[Bill Moseley <moseley@hank.org>]

On my laptop I removed the xdm init.d links instead of the xdm package 
so when I update I get xdm back.  This time I decided to start using xdm 
to manage logins.

This caused icewm to no longer display the little mailbox icon, so it 
turned out that the problem was that MAIL was not being set when logging 
in with xdm.

>From what I gather, login(1) sets MAIL, but xdm bypasses login.

So, I'm wondering why MAIL is not being set with xdm (seem like it 
should) and I'd also like to understand how it gets set normally when 
using login -- e.g. is it read set in a startup script?  I assume 
there's a setting to say mail is in /var/mail/$USER.

Secondly, is there a simple explanation of the boot and login process 
for Debian?  Something that explains the order of programs and scripts 
run.

Thanks,


-- 
Bill Moseley
moseley@hank.org