Click to open or drop winmail.dat here
Also ATT00001.dat and .eml files with winmail.dat inside — read in your browser, never uploadedThere are no attachments in this file — only the message.
The message
Pictures from the internet inside the message are blocked, so the sender cannot see that you opened it. Scripts never run.
About the Winmail.dat Opener
You got an e-mail from someone who uses Outlook, and instead of the PDF or photos they sent, there is only one strange file: winmail.dat (sometimes called ATT00001.dat). Your mail app cannot open it.
That file is a package. Outlook put the message and all the attachments inside it. This free opener unpacks it in your browser: you see the message, the list of attachments, and you can save each file — or all of them at once in a ZIP.
The file is never uploaded. It is read on your own device.
Features
- Every attachment — PDF, Word, Excel, photos… with their real names, saved one by one
- All in one ZIP — one click for every attachment
- The message — subject, sender, date and the text, formatted as sent or as plain text
- Safe to read — no scripts run, and pictures from the internet are blocked
- Attached e-mails — files inside a forwarded message are listed too
- Also .eml files — drop the whole e-mail, and the winmail.dat inside is found
- Save the text — as .txt, as a web page, or as RTF for Word
What is winmail.dat?
Outlook can send e-mails in its own "Rich Text" format. Other mail programs — Gmail, Apple Mail, Thunderbird, phone apps — do not understand that format. So the message reaches them as one attachment called winmail.dat, in a format named TNEF (Transport Neutral Encapsulation Format).
Inside the winmail.dat there is:
| Inside winmail.dat | What this tool does with it |
|---|---|
| The attachments (PDF, Office files, photos…) | Lists them with name and size; one-click save; ZIP of all |
| The formatted message (HTML or RTF) | Shows it safely; save it as .html or .rtf |
| The plain text of the message | Shows it; copy it or save it as .txt |
| Subject, sender, date | Shows them at the top |
| An attached e-mail | Lists the files inside it as well |
| Meeting requests | Shows the subject and text; the calendar data is not turned into an invite |
How to stop getting winmail.dat
The fix is on the sender's side, in Outlook. Ask them to send to you in HTML or plain text format instead of Rich Text:
- In Outlook: File → Options → Mail → Compose messages in: HTML
- For one contact: open the contact's e-mail address and set Internet format → Send plain text only (the name of the option depends on the Outlook version)
- Exchange administrators can turn off TNEF for outside mail
Frequently asked questions
How do I open winmail.dat?
Save the winmail.dat attachment from your e-mail, then drop it on the box at the top of this page. The attachments inside are listed at once — click Save next to each one, or Save all attachments (ZIP).
Is winmail.dat a virus?
No, it is a normal Outlook format. But the files inside are whatever the sender attached — treat them like any e-mail attachment, and only open files you expect. This tool never opens or runs them; it only lets you save them.
Can I open winmail.dat on an iPhone or Android phone?
Yes. Save the attachment to your phone's files, open this page, tap the box and choose the file. Then save the attachments you need.
What is ATT00001.dat?
The same thing with another name. Some mail programs rename winmail.dat to ATT00001.dat. Drop it here the same way.
Why are some pictures in the message missing?
Pictures that come from the internet are blocked on purpose. Loading them would tell the sender that you opened the mail. Pictures sent inside the e-mail are shown.
Is my e-mail uploaded?
No. The file is read by your own browser and is never sent to a server.
Related tools
- Email Header Analyzer — see where an e-mail really came from
- Zip and Unzip Files — open the ZIP of attachments, or make one
- DOCX Viewer — read a Word attachment without Word
- Excel Viewer — read an Excel attachment without Excel
- PPTX Viewer — look at a PowerPoint attachment
How to use it
- Save the winmail.dat (or ATT00001.dat) attachment from your e-mail
- Drop it on the box, or click the box to choose the file
- Click Save next to an attachment to download it — or Save all attachments (ZIP)
- Read the message below the list; switch between As sent and Plain text
- Use Copy text or the save buttons to keep the message
