Valerie Harper and Dick Van Dyke Will Make Guest Appearances on "Signed, Sealed, Delivered"

Stage and screen stars Valerie Harper and Dick Van Dyke will appear on two episodes apiece of the new Hallmark Channel series "Signed, Sealed, Delivered," according to

The new series, according to Deadline, concerns "an intrepid group of mail detectives in the Dead Letter Office who will deliver every last lost and dead letter to its rightful owner just when the recipient needs it most."

Harper will play the supervisor of the team in the first two episodes of the comedic drama; Van Dyke will appear in the second two episodes in the same role. A different TV icon will play the part every other episode.

The upcoming series is created and executive-produced by Martha Williamson. The cast will feature Eric Mabius, Daphne Zuniga, Kristin Booth, Crystal Lowe and Geoff Gustafson.