One of the IMAP servers (server3) is down. We are investigating.
Update: Server is back up and running again
Update 2: In a possibly unrelated issue, the frontend servers got confused about the up-ness status of one of the backends, so users who randomised to the backend (approx 1/4 of all users) were getting outage notifications. Users of /beta/ were unaffected. Approx 1/4 of web site viewers (not associated with the site, only the IP address they connected from) would also have seen errors. This is now resolved.
