I've just been looking over our mail queues, and noticed that anything going to @me.com is sitting there. When I hover over it I get:
"host or domain name not found. name service error for name=me.com. type=mx: host not found, try again"
All other mail is fine, and I can resolve me.com no problem and also nslookup gives me the ip, etc.
Kind of baffled...