Yesterday, Office 365 experienced a significant outage across most of the US and Europe as reported by sites like downdetector.com and MSPmentor.net leaving customers unable to log-in to Exchange Online to read, respond, send, or receive new emails. Many of our customers that have already migrated to Office 365 believed these types of events were a thing of the past. The belief was that moving to Office 365 would simplify operations in the hopes they could get out of the game of keeping Exchange servers up and running. However, one of the biggest trade-offs made was greater control of availability and uptime in the event of server failure. The best practice had always been to cluster Exchange servers for HA and replicated their data offsite using DAGs. Unfortunately, when they migrated to Office 365 they gave up the control of uptime and failover.