A short while ago I happened to see a message that Serge posted on my wall this morning. I did not receive an e-mail notification for it, so could easily have missed it.
I know that this function worked last night, because I got a couple of messages that way.
I got a message some minutes ago too.
I just tested it and it seems to be fine now. Perhaps some gremlins got in there and ate a few messages… 
Let me know if this keeps happening.
Yes, it is working again, a message from Vera got through this afternoon. Thanks!