.DBX

Файл DBX

Outlook Express E-mail Folder File
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A DBX file is a mail folder from Microsoft Outlook Express - each folder (Inbox, Sent Items, etc.) is its own .dbx file. Outlook Express is discontinued, so to read old DBX mail you import it into Windows Live Mail or extract messages to EML with DBXtract. DBX is not the same as Outlook's PST format.

Разработчик: Microsoft Corporation Категория: Файлы электронной почты MIME: application/octet-stream
ОТКРЫВАЕТСЯ НА Windows
Связанные: .RPMSG · .EML · .MSG · .MBOX

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Последняя проверка: Jun 25, 2026

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Что такое формат файла DBX?

.dbx files store the contents of a mail folder created by Microsoft Outlook Express, with each folder kept as a separate binary file along with B-tree index data for faster message access. .dbx files have a hard upper size limit of 2 GB, but the safest and most practical size is up to 300 MB - larger files can easily get corrupted, even during the compacting process. The format is proprietary, developed by Microsoft for Outlook Express, an email client no longer included in Windows systems since Windows 7.

Each .dbx file begins with the 4-byte signature CF AD 12 FE at offset 0. Deleted messages remain inside the file and continue to occupy space until the store is explicitly compacted. The .dbx format replaced the earlier Outlook Express 4 pair of .MBX and .idx files, and was itself frozen when Outlook Express 6 was discontinued.

Outlook Express by default creates a .dbx file for each mail folder per user. Default program settings configure the folder location to be Documents and Settings, where users can find the following files:

  • Folders.dbx - stores the index of all mailboxes and is used to restore the file structure in case of corruption or loss.
  • Offline.dbx - access data for IMAP or Hotmail accounts.
  • Inbox.dbx - inbox messages.
  • Sent Items.dbx - sent messages.
  • Drafts.dbx - message drafts.
  • Deleted Items.dbx - the recycle bin for Outlook Express messages.

Messages stored in .dbx mailbox files can be imported into applications that replaced Outlook Express, namely Windows Mail and Windows Live Mail, using the appropriate menu option. Many third-party tools for converting .dbx into other formats - for example .PST or .EML - are available. Note that .dbx is entirely distinct from Outlook's .pst format; Outlook Express and Microsoft Outlook are different programs. .dbx files should not be opened manually, as doing so may cause Outlook Express not to function properly or result in file corruption. Recovering lost data requires use of specialized tools and it may not always be possible to recover everything.

Безопасность и защита

РИСК: MEDIUM

A .dbx is passive data, but the mail inside is the real exposure: old e-mail can hold saved passwords, personal data and live attachments - treat an inherited store as sensitive. Old attachments may contain dormant malware, so scan before opening anything extracted. The format is fragile near its 2 GB limit, so always work on a COPY of the store and never the original. Avoid sketchy "free DBX viewer" download sites; stick to DBXtract (oehelp.com), Aid4Mail or DataNumen.

Детали формата

в двух словах
ПОЛНОЕ НАЗВАНИЕOutlook Express E-mail Folder Fileтакже известен как Outlook Express message store, DBX mail folder
РАЗРАБОТЧИКMicrosoft Corporationс 1997 (Outlook Express 4 / 5 message store; .dbx introduced with Outlook Express 5, 1999)
MIME-ТИПapplication/octet-stream
ТИПProprietary binary mailbox store (one folder per file)
СВЯЗАННЫЕ.rpmsg.eml.msg.mbox
Это расширение также используется в…
  • Visual FoxPro / DataBase indeX - Some database tools use .dbx for a database or index file - unrelated to Outlook Express mail.
  • DesignXpress / AVG / Cisco config files - Various apps have reused .dbx for project, antivirus or device-config data; the database here is the Microsoft Outlook Express mail store.
MAGIC BYTES · СИГНАТУРА ФАЙЛА
СМЕЩЕНИЕ
00010203
HEX
CFAD12FE
ASCII
····
Outlook Express DBX files begin with the 4-byte signature CF AD 12 FE, followed by a version/type marker that distinguishes message stores (Inbox.dbx etc.), the master Folders.dbx index, and the Offline.dbx / Pop3uidl.dbx control files. This is unrelated to other formats that reuse the .dbx extension.

Программы, открывающие файлы DBX

Windows4 apps
Windows Live Mail Бесплатно Last client that imports Outlook Express stores: File > Import messages > Microsoft Outlook Express 6. (Discontinued by Microsoft - install only from trusted archives.)
Aid4Mail Платно Convert/migrate DBX stores into PST, MBOX, EML or directly into Outlook/other clients.
DBXtract Бесплатно Extracts individual messages from a .dbx (even damaged ones) to .eml files you can open anywhere - the classic recovery tool.
DataNumen Outlook Express Repair Платно Repair and recover messages from corrupted .dbx files (e.g. ones that hit the 2 GB limit).

Технические подробности

глубокая спецификация
File structureBinary B-tree store; each mail folder is kept in its own `.dbx` file
Magic bytes`CF AD 12 FE` at offset 0, followed by a type marker that distinguishes message stores, the folder index, and control files
Byte orderLittle-endian
Hard size limit2 GB per `.dbx` file; corruption risk increases significantly as the file approaches this ceiling
CompressionNone - message bodies are stored uncompressed
EncryptionNone - content is stored in plain binary form on disk
MIME type`application/octet-stream` (also recognized as `application/x-dbx`)
Message format storedRaw RFC 822 / MIME message bodies, stored after the B-tree index region
Deleted message handlingDeleted messages remain physically inside the file and occupy space until the store is manually compacted
Master index file`Folders.dbx` holds the index of all mail folders and is used to reconstruct the full folder tree
Format lineage`.dbx` replaced the OE4 `.mbx` / `.idx` pair (introduced 1999) and was frozen at Outlook Express 6; incompatible with the earlier OE4 format
Associated platformWindows 98, Windows 2000, Windows XP; Outlook Express was removed starting with Windows Vista
Superseded byWindows Mail (stores messages as individual `.eml` files, Vista+) and Windows Live Mail; Microsoft Outlook uses `.pst` / `.ost`
Default storage pathUser profile under `Documents and Settings\[username]\Local Settings\Application Data\Identities\`
Repair and recoveryCorruption is common as files approach the 2 GB limit; dedicated DBX repair tools are required since manual editing will corrupt the binary store
Выпущен1997 (Outlook Express 4 / 5 message store; .dbx introduced with Outlook Express 5, 1999)
Последняя версияOutlook Express 6 (2001); format frozen - Outlook Express discontinued after Windows XP
Спецификацияen.wikipedia.org

Конвертации DBX

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Часто задаваемые вопросы

How do I open a DBX file without Outlook Express?
Outlook Express is gone, so import the .dbx into Windows Live Mail, or extract the messages to .eml with DBXtract (which opens in any modern client). For Outlook, convert DBX to PST.
Is a DBX file the same as an Outlook PST file?
No. DBX is Outlook EXPRESS (one file per folder); PST is Microsoft Outlook (one file for the whole mailbox). They are different programs and formats - you must convert DBX to PST to use the mail in Outlook.
How do I convert DBX to PST?
Import the .dbx into Windows Live Mail then export to Outlook, or use a dedicated DBX-to-PST converter such as Aid4Mail. Modern Outlook has no built-in DBX import.
Why is my Outlook Express Inbox corrupted?
The most common cause is hitting the ~2 GB-per-.dbx size limit (the Inbox usually fills first). Use a DBX repair tool (DataNumen, DBXtract) on a copy of the file to recover the messages.
Where are Outlook Express DBX files stored?
Under the user's hidden Identities folder (e.g. Documents and Settings\<user>\Local Settings\Application Data\Identities\{GUID}\Microsoft\Outlook Express). Each folder is a separate .dbx, indexed by Folders.dbx.
Can I read a DBX file on a Mac or Linux?
Not directly - there is no native DBX client. Extract the messages to .eml or MBOX on a Windows PC (DBXtract/Aid4Mail), then open the EML/MBOX in Apple Mail, Thunderbird or any modern client.

Ссылки

1Wikipedia - Outlook Express (DBX message store)en.wikipedia.org
2OEHelp - DBXtract (free DBX message extractor)www.oehelp.com

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