Canada’s The Hospital for Sick Children AS 46626 SICKKIDS-AS-01 dropped out of the May 2013 for world medical organizations from CBL data. In April they ranked #1 with 21,912 spam messages, and in May they dropped to #27 with only 28 messages. In April they really only spammed for one week, as you can see in the big spike in the graph. Of course, the hospital itself probably didn’t knowingly send the spam; usually they’ve been compromised by botnets or phishing or some other breach, but hospital patients and other customers won’t necessarily know that if they receive some of it. And if their security is lax enough to let in things that emit spam, what else has been compromised? This is why hospitals are quick to squelch outgoing spam and fix the underlying security problems.

-jsq