By the "Sorry, to prevent 'Spam', only subscribers may send more than 10 messages in a 24 hour period." message.
I tried to send a message to my opponent who was out of time, that he was gonna be sunk if he didn't move soon, but as I had already used up my miserable allocation of 10 messages I had no choice but to reluctantly claim the win from this SUBSCRIBER.
The moral;
Messing with non subs affects subs too.