Can non-registered representatives be contacted for patent application actions?

No, non-registered representatives should not be contacted for patent application actions, even if they appear to be authorized by the attorney or agent of record. The MPEP clearly states:

In addition, non-registered representatives of the practitioner of record should not be contacted for such actions, even if apparently authorized by the attorney or agent of record.

This restriction helps maintain the integrity of the patent application process and ensures that only qualified, registered practitioners are involved in critical communications.