If you need to match all the senders from your domain and not just specific ones do the following:

in the file /etc/postfix/disclaimer_addresses add your domains like:

example.com

sub.example.com

and then change the following line at /etc/postfix/disclaimer script:

original: from_address=`grep -m 1 "From:" in.$$ | cut -d "<" -f 2 | cut -d ">" -f 1`

after the change: from_address=`grep -m 1 "From:" in.$$ | cut -d "<" -f 2 | cut -d ">" -f 1 | cut -d "@" -f 2`