*despite the fact that sending is impossible to block I may not use it to harass the BBEG in the middle of the night.
*or any other time of day for that matter
*despite the fact that in no place in the description does it say the receiver knows the identity of the sender the king will figure out you were the one who caused him to flub the yearly address.
*Sending only allows non magical words. It is most certainly not a vehicle to deliver a sequence of 25 spells of the power word line.