What is the EDB file format?
.edb is the extension used by database files created by Microsoft Exchange Server. .edb files serve as the main storage for data generated by e-mail mailboxes in Exchange. An .edb file contains all mailbox data, including non-SMTP messages, emails, tasks, contacts, logs, notes, and calendars.
EDB file characteristics
.edb uses a B-tree structure with parent and child nodes organized into fixed-size database pages (4 KB by default). Exchange Server accesses .edb data through the Extensible Storage Engine (ESE, also called "Jet Blue"), a transactional, write-ahead-log database engine built into Windows. ESE databases carry a characteristic file-header signature (0x89ABCDEF in little-endian form, stored at offset 4), which identifies any ESE-format file. The same engine also backs the Windows Search index (Windows.edb) and Active Directory (ntds.dit).
Main EDB files
Older Exchange versions (2000 and 2003) used two main database files: Priv1.edb (private mailbox store) and Pub1.edb (public folder store). Each was accompanied by a .stm file that held raw SMTP streaming data. Exchange Server 2007 and later merged these into a single .edb per mailbox database and removed the .stm pairing; public folders moved into their own separate .edb database.
Additional information
.edbformat is supported only on the Windows operating system.- ESE was designed for quick, concurrent access to many database pages simultaneously.
- Administrators use the built-in
eseutilcommand to repair (/p), defragment (/d), or verify the integrity (/g) of an.edbfile. - Mailbox data can be exported to a
.pstfile using theNew-MailboxExportRequestPowerShell cmdlet.
Security & safety
RISK: MEDIUMAn EDB itself is passive data, but the realistic risks are operational, not malware. It is a live, locked server database: never copy, move or hand-edit an in-use EDB, and never delete the matching .log files - doing so can corrupt the store and lose every mailbox in it. Always work on a backup copy, and use eseutil only with care (a hard repair can drop data). EDB files contain an entire organisation's e-mail, so they are highly sensitive - handle exports under proper access controls. Download third-party EDB tools only from the vendor's official site. Separately, a large Windows.edb (the Search index) is safe to rebuild via Indexing Options if it bloats - that's unrelated to Exchange mail.
Format details
in a nutshell- Windows Search index (Windows.edb / Windows.db) - Windows Search keeps its file/content index as Windows.edb in ProgramData\Microsoft\Search; it's a system index you rebuild via Indexing Options, not something you open.
- Microsoft Active Directory store - Active Directory's database (ntds.dit) uses the same ESE engine; it's a domain-controller system file managed only by Windows Server tools.
Programs that open EDB files
Windows4 apps
Kernel Exchange EDB Viewer
Free Free read-only viewer: open an offline EDB to browse mailboxes and items without Exchange. Good for inspection before a paid export.
Microsoft Exchange Server (eseutil + New-MailboxExportRequest)
Paid On the Exchange server: use eseutil to check/repair the EDB, mount the database, then New-MailboxExportRequest to export mailboxes to PST. The native, authoritative route.
Stellar Converter for EDB
Paid Open an offline/orphaned .edb without a live Exchange and export mailboxes to PST/MSG/EML. Free trial previews items. (Formerly 'Mailbox Exchange Recovery'.)
Microsoft Windows (Exchange host)
Built-in EDB databases only run on Windows Server hosting Exchange; Windows itself doesn't 'open' an EDB - it's the platform Exchange runs on. Technical details
deep spec| Format type | Proprietary binary ESE (Extensible Storage Engine) B-tree database |
| Underlying engine | Extensible Storage Engine (ESE, also known as "Jet Blue"), a transactional database engine built into Windows Server |
| File header signature | 0xEF CD AB 89 at byte offset 4 (little-endian representation of 0x89ABCDEF); the preceding 4 bytes are a page checksum |
| MIME type | application/octet-stream |
| Default page size | 4 KB per database page; newer ESE versions support 8 KB or 32 KB page sizes |
| Data structure | B-tree pages containing tables, columns, and indexes; parent-child node relationships enable rapid keyed lookups across millions of records |
| Transaction logging | Write-ahead logging via paired .log files (e.g., E00.log); required for crash recovery and point-in-time restore |
| Integrity verification | Per-page checksums embedded in each database page; eseutil /g performs an offline integrity check across the entire store |
| Legacy streaming companion | .stm file (Priv1.stm / Pub1.stm) held raw SMTP streaming data in Exchange 2000 and 2003; pairing was removed in Exchange 2007 and later |
| Mailbox export command | New-MailboxExportRequest PowerShell cmdlet exports mailbox contents to a .pst file |
| Maintenance utility | eseutil.exe - /d for offline defragmentation (compaction), /p for database repair, /g for integrity verification |
| Platform support | Windows Server only; the ESE engine has no native Linux or macOS implementation |
| Other ESE-backed files | Windows Search index (Windows.edb), Active Directory database (ntds.dit), and SRUM database (SRUDB.dat) share the same ESE on-disk format |
| Database format version | ESE format version is stored in the file header; version upgrades are one-way - downgrading requires restoring from a backup |
| Released | Microsoft Exchange Server (ESE engine, 1990s); modern .edb store |
| Specification | learn.microsoft.com |
EDB conversions
Community Q&A
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