It's even a bit worse, i cannot send messages either (tried sending thire a reply, wich didn't work, then tried sending a message, wich doesn't work either).
The error i get is that it doesn't know a player by the name <blank>, and that i didn't enter a subject in the subject line. The thing is, i DID enter a name (namely 'thire'😉 and also a subject (namely 'Reply'😉 all without the quotes.
Seems that there was (is?) some glitch with outgoing messages today indeed. I did not see any error messages and my messages were received all right, but none of them appeared in the "Sent Items".