[exim] Forwarders router

Hi,

By default cPanel allows any forwarders to be set.

I wonder how can be a router configured to block forwarded emails to an
ISP (aol.com or hotmail..) but bypass the normal emails

It appears cPanel uses the following router to handle them:
======================================
virtual_aliases_nostar:
driver = redirect
allow_defer
allow_fail
data = ${if
exists{/etc/valiases/$domain}{${lookup{$local_part@$domain}lsearch{/etc/valiases/$domain}}}}
file_transport = address_file
group = mail
pipe_transport = virtual_address_pipe
retry_use_local_part
domains = lsearch;/etc/localdomains
unseen
=======================================

also i found another one below the first one provided:
=================================
virtual_aliases:
driver = redirect
allow_defer
allow_fail
data = ${if
exists{/etc/valiases/$domain}{${lookup{*}lsearch{/etc/valiases/$domain}}}}
file_transport = address_file
group = mail
pipe_transport = virtual_address_pipe
domains = lsearch;/etc/localdomains
retry_use_local_part

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

Does anyone know how to configure a 'condition' or another router to
filter forwarders?
Would it be possible to use exim.pl? If so, does anyone have some
examples of such config?

Thanks in advance,
Eugene