Is there a way to make an entity spawn near a specific player?

I want to make something like a mail system that can be used to send messages to a specific player in the world. I need to be able to select a player and send them an entity that has some specific content (that is, the inventory of this entity should be preserved). The idea is that the messages get to the player (say, as if a pigeon arrives with a letter), and not just sent by coordinates.

Is there any way to do this?