content: Every cloud/webmail provider has had outages in the past.  What's of concern is that as we are becoming increasingly reliant on cloud technologies they aren't getting necessarily more reliable.  That's not to say that local servers aren't also vulnerable to failures etc., but as IT giants take more and more of the computing into the cloud, it becomes a putting all eggs in just a few baskets.  One local exchange server going down doesn't affect millions of users, but one cloud provider going down can affect huge chunks of users, from the casual to mission critical.