[exim] trying to block non-special case addresses

I would like to be able to accept my defined email addresses as well as
certain addresses I make-up on the fly. The addresses I make up on the
fly are something like "bestbuycom@???" when I order something
from their site. (It allows me to track where spam comes from and eaily
block the one that starts getting spam later).

my server has a virtual /etc/shadow passwd file for each site. so I can
find the virtual usernames there. Then I just need to check if the
email address ends in "com@???". If neither matches, I want to
reject the email.

During my ACL, I have the following to force verification:
require verify = recipient

Then in my routers, I've tried defining the following router which
doesn't seem to decline anything (i'm looking to decline an address like
"akfdjlkf@???" but allow virtual addresses like
"terry@???" and allow my dynamic addresses ending in
"com@???").



Am I doing something that's always returning true?

Thanks for any help.
tc




==========================================

virtual_aliases_local_and_com:
   driver = redirect
   !condition = ${\
                       if or{\

{lookup{$local_part}lsearch{/home/mysitedir/etc/mysite.com/shadow}}\
                         {  match{$local_part}{.*com\$}   }\
                       }\
                 }
   allow_fail
   data = :fail: $local_part email address at this $domain was not found
   verify_only