Wondrous item, common
As per this Envelope of Sending magic item whenever the sheet of paper or else the tiny item has been placed in this envelope, however the user could specify the recipient until unless the recipient’s name (or a name the sender associates with the recipient) is written on it. If the recipient lives within five miles of the envelope, the letter will be filed towards them and they will receive it within 10 minutes. If it isn’t, the letter will not be sent. If the recipient moves outside the designated range or transports itself to another plane, the letter will be delivered at the exact same place it is sent.