#!/bin/sh 
# Localize these. 
INSPECT_DIR=/var/spool/filter
SENDMAIL=/usr/sbin/sendmail

# For multiple domains:
DOMAIN_A_ADDRESSES=/etc/postfix/domain_a_addresses
DOMAIN_B_ADDRESSES=/etc/postfix/domain_b_addresses
# Exit codes from <sysexits.h> 
EX_TEMPFAIL=75 
EX_UNAVAILABLE=69 

# Clean up when done or when aborting. 
trap "rm -f in.$$" 0 1 2 3 15 

# Start processing. 
cd $INSPECT_DIR || { echo $INSPECT_DIR does not exist; exit 
$EX_TEMPFAIL; }

cat >in.$$ || { echo Cannot save mail to file; exit $EX_TEMPFAIL; }

from_domain=`grep -m1 "^From: " in.$$ | cut -f 2 -d "@" | cut -d ">" -f 1`

# hsmedia.co.uk domain name disclaimer
if [ `grep -wi ^${from_domain}$ ${DOMAIN_A_ADDRESSES}` ]; then
  /usr/bin/altermime --input=in.$$ \
                   --disclaimer=/etc/postfix/domain_a_disclaimer.txt \
                   --disclaimer-html=/etc/postfix/domain_a_disclaimer.txt.html || \
                    { echo Message content rejected; exit $EX_UNAVAILABLE; }
fi

if [ `grep -wi ^${from_domain}$ ${DOMAIN_B_ADDRESSES}` ]; then
  /usr/bin/altermime --input=in.$$ \
                   --disclaimer=/etc/postfix/domain_b_disclaimer.txt \
                   --disclaimer-html=/etc/postfix/domain_b_disclaimer.txt.html || \
                    { echo Message content rejected; exit $EX_UNAVAILABLE; }
fi

$SENDMAIL "$@" <in.$$

exit $?

<below every submission and smtp it has this below (since I am running two virtual hosts on virtualmin all using their own dedicated IPs:>
    -o content_filter=dfilt:

dfilt     unix    -       n       n       -       -       pipe
    flags=Rq user=filter argv=/etc/postfix/disclaimer -f ${sender} -- ${recipient}