Spend hours to figure this, when you are re-injecting the mails after attaching the disclaimer with altermime make sure to add the -oi parameter to sendmail.postfix. This will basically ignore the dot '.' as the end of mail. Otherwise you end up receiving half mails..
i.e.
instead of
$SENDMAIL "$@" <in.$$
do this
$SENDMAIL -oi "$@" <in.$$
