Could the Sending spell be used to send a message to a target who was killed and reborn in the Nine Hells?
The target was a PC (warlock of Dispater (Titivilus?)) who accomplished a very important task for his master and was granted the boon to be reborn as chain devil, not a lemure. Some time after that he died and was reborn at Dis of Nine Hells as a chain devil by its infernal contract.
The spellcaster who is casting sending doesn't know this fact and assumes that the target is alive. He knows the target's name and had close connections with him.