01 / Fast steps
- Drop or select the winmail.dat file.
- The container is decoded automatically.
- Download the attachments it was hiding.
Open winmail.dat
Drop the winmail.dat you received instead of the attachment and get the real files back, with their original names.
drop your files anywhere in this area
Your files never leave your device. This tool even works offline.
DAT
02 / Best for
- Recover an invoice or contract a colleague sent from Outlook.
- Open the attachment on a phone or a Mac that shows only winmail.dat.
- Read the message text that came with the encapsulated attachment.
03 / Why here
- Long file names are restored from the MAPI properties, so you get quarterly-report.xlsx rather than QUARTE~1.XLS.
- Email attachments are private by nature: the container is decoded in your browser and nothing is uploaded.
- Extracts every attachment in one pass, plus the plain text message when the container carries one.
04 / Keep in mind
- A winmail.dat that carries only formatting, with no attachment and no message, has nothing to extract.
- The Rich Text version of the message body is not converted, only the plain text one when present.
- Files renamed to .dat that are not TNEF containers are rejected rather than guessed at.
Tool connections
Related tools
01winmail.dat to PDFTurn the winmail.dat file Outlook sent you into one readable PDF that carries the message and its attachments inside it.02Open a PEC AttachmentDrop the postacert.eml of a certified email and get the signed document out of it, in one pass and without downloading anything in between.03Identify File TypeFind out what a file really is by reading its content instead of its extension, then open it with the tool that reads it.04E-Invoice XML to PDFOpen an Italian e-invoice XML or XML.P7M file and read it as a normal PDF, entirely in your browser.05MSG to EMLOpen an Outlook MSG file without Outlook: read the message and get its attachments back.06DOCX ViewerOpen and read a Word DOCX document without Word, entirely in your browser.
Good to know
Questions & answers
01What is winmail.dat and why did I get one?
It is a TNEF container, short for Transport Neutral Encapsulation Format. When Outlook sends a message in its Rich Text format, it packs the formatting and every attachment into one binary file called winmail.dat. Mail clients that understand TNEF unpack it invisibly; everything else shows you the container itself. So the attachment is not lost, it is wrapped: the sender chose a format only Outlook fully speaks.
02How do I stop receiving winmail.dat files?
The fix is on the sending side, not yours. The sender has to compose in HTML or plain text instead of Rich Text, either for that message or as the default in their Outlook settings. Asking them to resend as HTML usually solves it in one step, which is worth knowing because no setting on your end can undo the encapsulation.
03Why do the file names come back correct here?
Because two names live in the container. The attachment title field only holds the old 8.3 short name, which is why many tools hand you QUARTE~1.XLS, while the full name sits in a MAPI property block alongside it. This tool reads that block and prefers the long name, falling back to the short one only when there is nothing better.
04Is the file uploaded anywhere?
No. The container is decoded by JavaScript in your browser tab and the attachments are written straight to your disk. That is the point: winmail.dat files usually arrive in work email, so the attachment inside is often exactly the kind of document that should not be handed to a stranger to unpack.
05Can a winmail.dat file contain a virus?
The container itself is inert data: a packing format, not a program, and nothing runs when it is opened here. The real attachments packed inside carry exactly the same risk they would have had as ordinary attachments, so treat an extracted executable or a macro document with the usual caution. Everything on this page is unpacked locally in your browser and nothing is ever executed.
06Why is the winmail.dat so large when the email looks empty?
Because everything is in there. When Outlook packs a message in TNEF, the formatted body and every real attachment travel inside winmail.dat, and the visible message is left with nothing. An email that shows no attachments but weighs ten megabytes is the classic sign: the documents you were promised are all inside the blob, and unpacking it gets them back.
07Can I open winmail.dat on iPhone or Android?
Yes, right here: the page runs in the phone browser the same way it runs on a desktop, with no app to install. Save the winmail.dat attachment from your mail app, load it on this page and download the extracted files. The processing happens on the phone itself, so nothing is uploaded along the way.