Mailbox access unavailable

Mailbox access was unavailable for about four and a half hours in the early morning of 17 August.

Access over IMAP and through the webmail interface stopped responding at 04:33 UTC, after a routine overnight maintenance task on the mailbox server did not complete as intended. Incoming mail was held while the service was unavailable and was delivered once it returned, so no mail was lost. We identified the cause and restored access at 09:07 UTC.