Message pod

A message pod was 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 would only open when touched by the person for whom the message was intended. Much like the outer plasmic shell of a TARDIS, the exterior of the pod was nearly invulnerable to outside forces. The message pod would 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)