Exchange 2013 uses Managed Availability to monitor its own health. One part of this monitoring is achieved through the use of synthetic transactions, mimicking regular user activity, such as accessing mailboxes, send/receive e-mail, etc. For this to work properly, the monitoring system uses so-called Health Mailboxes. These are just regular mailboxes (with a regular AD account), but are created automatically and used for the sole purpose of health monitoring. Depending on the CU-version of Exchange 2013, these are created for every database on every CAS (or just one per CAS and one per database, starting from CU6).

Sometimes, these mailboxes may become corrupt or unusable, in which case the  ...