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Extensible storage engine (ese) database file (edb) format

Microsoft Exchange Server database uses Extensible Storage Engine (ESE) which is designed for single client-server architecture. The Exchange Server directly accesses the data from ESE and the database here is stored in hierarchical storage format which includes the messages, folders, attachments, message properties etc. The data stored in each table may have varying property. The Information Store and ESE collaboratively makes up client-server based messaging service for small and large enterprises.

In many of its technologies like Access or FoxPro, Microsoft uses the Joint Engine Technology (JET). There are two variants of JET engine: JET Red and JET Blue. Microsoft Office applications like Access uses JET Red that provides a standalone single user database. Since it was not developed for a multi-user access and thus considering this limitation, the JET Blue was developed that suited the multi-user requirement like Exchange Server. From the time this technology is used in Exchange server, it has evolved to large extent and is incomparable to its original form. Microsoft renamed this JET technology as Extensible Storage Engine (ESE).

MIME types

The actual mime type of the ESDEB format is unspecified

File signature

The ESEDB has the following file signature: hexadecimal: ef cd ab 89 (at offset 4)

File types

The ESEDB has the following file signature:

  • hexadecimal: ef cd ab 89 (at offset 4)

ESEDB distinguishes between the following types:

  • database (.edb, .sdb, ...)
  • streaming file (.stm)

Database (.edb)

The EDB file stores rich text data of Exchange Server and is known as its proprietary store. MAPI, HTTPS, and SMTP messages are stored in the EDB file with database arranged in B-Tree structure. The data gets saved into 4 KB pages (or multiple of 4 depending upon version of Exchange Server used) and these pages contain data, checksum, pointers, headers etc.

Streaming File (.stm)

The Streaming data file (STM) is introduced with Exchange 2000 Server. This file stores the Internet MIME formatted content like video, images, audio, or other multimedia. There are also multiple versions of the ESEDB format. Basically the database that needs to be streamed is saved here. This file format was provided by Microsoft in addition to EDB in order to optimize the application performance for the type of database it stores. STM is excluded from database structure after Exchange 2003 edition.

There are also multiple versions of the ESEDB format.


The ESEDB basically is an ISAM database file format.

The ESEDB format is used by many Microsoft applications to store data such as:

  • Active Directory (NTDS)
  • Cortana
  • File Replication service (FRS)
  • Windows Internet Name service (WINS)
  • DHCP
  • Security Configuration Engine (SCE)
  • Certificate Server
  • Terminal Services Session folder
  • Terminal Services Licensing service
  • Catalog database
  • Help and Support Services
  • Directory Synchronization service (MSDSS)
  • Remote Storage (RSS)
  • Phone Book service
  • Single Instance Store (SIS) Groveler
  • Windows NT Backup/Restore
  • Exchange store
  • Microsoft Exchange folder (SRS and DXA)
  • Key Management service (KMS)
  • Instant Messaging
  • Windows (Vista) Mail
  • Content Indexing/Windows (Desktop) Search

Tile Data Layer database


Tools that are provided with the ESE engine: