Summary:
What is the "Milter to error state" message? Is this message something I should be concerned about?

Question: What is the Milter (pm): to error state message?

Answer:

PerfectMail is implemented using an integration interface called Milter to our Sendmail message transport agent. Spammers will often connect to your PerfectMail server but close their connections, they leave them open. When the connection times out it is dropped and the communication between PerfectMail and Sendmail is interrupted. This interruption creates the Milter (pm): to error state message in the Transmission Log.

This is normal behavior and should not cause any concern, unless it appears on every message. In that case, the PerfectMail service may have stopped. In that case, restart the PerfectMail service using the dashboard.

FYI: PerfectMail has an independent process called pmCheck that looks for any problems with services and configurations. If it finds an issue, pmCheck will fix the problem and restart any services as required.