The README file says: At least one plugin MUST allow or deny the RCPT command to enable receiving mail. The "check_relay" plugin is the standard plugin for this.
But in version 0.29, the "check_relay" plugin split into two plugins: "check_relay" and "rcpt_ok". "rcpt_ok" is the one that actually hooks into RCPT now, so shouldn't the README file say "rcpt_ok" instead of "check_relay"?