creating a whitelist

I want to allow mail from some of my clients through without getting stopped.
I believe the best way to do this is via a "whitelist".

I have found the following information and would like some feedback on whether it is correct, or if there is a better way of achieving the same end result.

You can create a whitelist that will accept messages from certain addresses or domains. For example:

#
# main.cf
#
smtpd recipientrestrictions =
permit_mynetworks
reject unauthdestination
...
check senderaccess hash:/etc/postfix/whitelist
reject rblclient dnsbl.njabl.org
...

#
# whitelist
#
@customer_domain.com OK

Make sure the whitelist check occurs before the reject rblclient check. Remember that email addresses are easily faked. Whenever you add whitelisting to your configuration be very careful that you don't expose your server to open relaying. Make sure that your whitelisting occurs after reject unauthdestination (or another rejection restriction).


TIA

Tony