Whether the appeal against the insurer's letter is admissible before the cantonal social insurance court.
The appeal is inadmissible because, on the record, it cannot be determined whether the dispute falls under social insurance law or private insurance law, and in either case the cantonal court cannot hear the case in this procedural posture.
If LPGA applies, the appeal is premature because there is no objection decision. If the case is governed by the insurance contract law, it is a private-law dispute outside the court's cantonal jurisdiction in this configuration.