I have been having a problem with Plesk 10.4.4 using Postfix and the Plesk Spamassassin:
Mails from SASL Authenticated local domain users was being tagged as Spam by Spamassassin, with, amongst others, RCVD_IN_PBL.
I fixed this by doing two things:
1) adding the following to the /etc/postfix/main.cf smtpd_sasl_authenticated_header = yes
2) adding the following to /etc/mail/spamassassin/local.cf (replace your.host.name with your hosts FQDN that shows up in mail headers) header SASL_AUTH_RCVD Received =~ /\(Authenticated sender: .*@.*\) by your.host.name \(Postfix\) with/ score SASL_AUTH_RCVD -10 describe SASL_AUTH_RCVD received from SASL authenticated user