Message pod

A message pod is a device used by the Time Lords as, essentially, a secure courier for delivery of messages or small objects to a specific recipient. The pod will only open when touched by person to whom the message is intended. Much like the outer plasmic shell of a TARDIS, the exterior of the pod is nearly invulnerable to outside forces. The message pod will usually pre-program its destination into a nearby TARDIS.

The Time Lords used a message pod to send the Doctor on a mission to Solos to deliver a set of ancient tablets to Ky, a Solonian resistance figure. (DW: The Mutants)