Postfix
There is a method to bypass RBL checking for certain addresses and domains in Postfix. This assumes that you are using RBL checking in the first place.
First, create an rbl_override file in /etc/postfix.
Place the domains and/or IP addresses you would like whitelisted into that file.
192.168.0.2
domain.com
subdomain.example.com
Create the hash of that file.
Edit the main.cf file.
Locate the section marked smpt_recipient_restrictions. You need to add the following to that.
Restart Postfix and you should be all set.
Change to the Postfix configuration directory. Usually this is in /etc/postfix.
Open the sender_access file or create it if it doesn't exist.
Add the email address you want rejected on a new line in the file followed by REJECT.
Save the file.
Create the server_access database with the postmap command
Edit the main.cf file and add the following
Restart Postfix
Check your logs to make sure everything is good.
Postfix has some spam fighting abilities built in. However, you will need to enable them for them to work. Just throw the code below into your main.cf file and restart Postfix. Voila.
permit_mynetworks,
permit_sasl_authenticated,
reject_unauth_pipelining,
reject_non_fqdn_recipient,
reject_non_fqdn_sender,
reject_unknown_recipient_domain,
reject_unauth_destination,
reject_invalid_hostname,
reject_rbl_client sbl.spamhaus.org,
reject_rbl_client xbl.spamhaus.org,
permit