OpenAnyFile
What is a .dbx file?
Outlook Express Mailbox is an email and contacts format developed by Microsoft, first released in 1999. It is usually created by Outlook Express 5–6.
One file per folder (Inbox.dbx, Sent Items.dbx). Windows Live Mail and Thunderbird can import them.
File details
| Full name | Outlook Express Mailbox |
|---|---|
| Category | Email & contacts |
| MIME type | application/x-outlook-express |
| Signature (magic bytes) | CF AD 12 FE |
| Developer | Microsoft |
| Introduced | 1999 |
| Opens with | Universal inspector |
| Uploaded? | No — read locally in your browser |
How to open a .dbx file
OpenAnyFile routes .dbx files to its universal inspector, which shows a hex view, the detected signature, checksums and any readable text.
- Drop your .dbx file on the box above, click it to choose the file, or paste it with Ctrl+V.
- The real format is detected from the file's first bytes — not just its name.
- The file opens in the universal inspector.
- Use fullscreen for a closer look, check its checksums, or download it back unchanged.
What works — and what does not
Works
Viewing and inspecting: a hex view, the detected signature, checksums and any readable text. Size, type, signature and checksums are always shown.
Does not work
A rendered view. This format has no open decoder, so you get a byte-level inspection and readable text instead.
Is it safe to open a .dbx file online?
Here, yes — because nothing is uploaded. Most "online viewers" send your file to their server. OpenAnyFile reads it with your browser's File API and decodes it on your own device, so there is no copy anywhere else. You can check: open your browser's network tab while opening a file — no upload appears.
Questions about .dbx files
Can I open a .dbx file without installing software?
Yes. OpenAnyFile opens .dbx files in your browser using its universal inspector. You get a hex view, the detected signature, checksums and any readable text, with nothing installed and no account.
How do I know a file is really a .dbx file?
Check its first bytes instead of its name. A genuine DBX file begins with CF AD 12 FE. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .dbx file uploaded anywhere?
No. The file is read locally by your browser and never sent to a server — it even works offline once the page has loaded.
Does it work on phones?
Yes — on Android and iPhone, in any modern browser. You can also install OpenAnyFile as an app.
Related formats
Other formats from the same family:
Format facts checked and page updated on September 25, 2026.