Best way to seal off a mail slot

Bulk Mail Clerk, see: Postal service workers · Bulk Mail Technician Ceiling Insulation Blower, see: Insulation workers · Cellist, see

Energy Efficient, Ideal for All Climates · Internal Brush Strip for Added Insulation and Privacy · New Design for All Thicknesses of Glass, and Even Insulating

mail slot catcher insulation or void fill inside to be able to protect the contents from Time sensitive and time slot deliveries; Show and trade fair freight

mail slot cover interior  Insulated Universal Single Side Surface Mount Matte Black Mail Slot Only 12 left in stock