[exim] local domain impersonating

Hey all

I see in my logs that these darn spammers are impersonating my local domains.

I currently have this ACL for my primary hostname.

# HELO is my hostname
drop    message   = "REJECTED - Bad HELO - Host impersonating [$sender_helo_name]"
         condition = ${if match{$sender_helo_name}{$primary_hostname}{yes}{no}}

My questions is, would anyone know how to expand this rule for all my local domain.

If anyone could assit, I would greatfully be appreciated.

Kind Regards
Brent Clark