Microsoft Exchange Server Database Utility Guide - I really hope you'll never need this guide 😉
"When a database is corrupt or damaged, data can be restored from backup or repaired using Eseutil. Eseutil is a command line utility that works with Extensible Storage Engine (ESE), database (.edb) files, streaming (.stm) files, and log (.log) files associated with an Information Store, in a given Storage Group. Eseutil is located in the C:\Program Files\Exchsrvr\Bin folder in Exchange Server 2000 and in Exchange Server 2003. The tool can be run on one database at a time from the command line and can be used to perform a range of database tasks from repair, offline defragmentation, and integrity checks in Exchange Server 5.5, Exchange Server 2000, and Exchange Server 2003."