[mew-int 3137] handling multiple smtp settings in one config file

I'm trying to set up a way for the
mailer to use different SMTP settings from within the same configuration 
file (which I am syncing among my various machines) depending on which 
machine
it's running on. I found an Emacs function called file-exists which
is supposed to test for the presence of a file, and so I tried to use 
this by I am
putting a differently-named empty file in my root directory on the 
different machines
that is intended to trigger the change. What I've written is like this:

(if (file-exists-p "/mail-u-tokyo")
(setq mew-smtp-port "25")
(setq mew-smtp-server "mail.l.u-tokyo.ac.jp")
)

(if (file-exists-p "/mail-home")
(setq mew-smtp-port "587")
(setq mew-smtp-server "mail.so-net.ne.jp")
)


But it's not working (probably I don't understand the function of 
file-exists-p). Does anyone have advice as to what I am doing wrong? Or 
perhaps there's a better way of doing this?

Regards,

Charles
-- 

---------------------------
A. Charles Muller

Graduate School of Humanities and Sociology
Faculty of Letters
University of Tokyo
7-3-1 Hongō, Bunkyō-ku
Tokyo 113-8654, Japan

Office Phone: 03-5841-3735

Web Site: Resources for East Asian Language and Thought
http://www.acmuller.net