exim worked; had to upgrade to exim4, which, for me, doesn't work

[p <pplaw@pcisys.net>]

on january 2, 2007,  i replaced an aging hard drive, running debian 
potato.  for the 3+ years  of running potato, i used mutt (exim and
fetchmail) to handle email.

ever since (jan. 2, '07), when i upgraded to sarge, i have not been
able to  configure exim4  (correctly), as when  i "fetchmail," open 
mutt, and look at the messages  in /var/mail/"me", i  get the error 
message, "mail delivery failed," for each email.


when open an email, i see this refernce to localhost:


	"the following address(es) failed:  

	pplaw@localhost

	   unroutable address"


(if i  could get it to recognize my email address as:

	"pplaw [at] pcisys.net",
 
instead of as, 

	"pplaw@localhost", 

then i think it would work.  that's where i'm stuck.)

my googling "unroutable  address" for   exim4 entries  and  reading 
the "exim4-doc-html" file(s) lead me to believe  that i may have to 
learn how to write code in order to have a realistic chance of fig-
uring out how exim4 (version 4.63-17) needs to be setup.   

on the other  hand, since  it's been  8 months,  and  counting,  it 
doesn't look like i'm going to be able to figure out exim4:

 1.  is there  a way  to use  mutt and fetchmail without setting up
     exim4?  (i pop3 my email from my isp.);

 2.  is  there another  text-based  email client  that can  be used 
     without trying to configure exim4? or 

 3.  is my  only hope to wait  and see if exim4 is someday upgraded
     to an easier configuration, one like the old "exim"?

 4.  as an aside,  why do the  exim4-configure windows have jibber-
     ish-looking borders?    

thx.