Does pfsense have?
Does pfsense have a good antispam package that someone could recommend? I don't mine if I have to pay a small fee to keep the RBL info up to date.
Use of an RBL is a part of the mail server package configuration and running an external smtp server on your firewall is a BadIdea for a host of reasons.
There are quite a few RBLs around, many are free within certain usage limits.
Once you set up your mail server on another box you can put pfSense packages to work. A couple of examples are:-
pfBlockerNG which can be fed lists of spammer IPs to drop, some updated hourly.
Snort or Suricata which can be configured to intercept attempts to compromise your mail server and block offenders.