TNEF explained

winmail.dat is a wrapper, not the file you wanted.

Outlook can encode rich-text properties and attachments in Microsoft's TNEF format. Other email clients may expose that container instead of its contents.

Workspace status

Ready · Local browser memory

Drop a file to recover attachments

Open it once. Reader, safety, headers, route, redaction, and export reuse the same in-memory source.

.EML
.MSG
.EMLX
winmail.dat
Processed locally. Files and filenames stay on this device.
Workflow

From source file to finished result

Runs locally
  1. Step 1

    Identify the TNEF container

  2. Step 2

    Decode its message and attachment records

  3. Step 3

    Download the original embedded files

What this workspace preserves

The common filename is winmail.dat

It can contain formatting, calendar data, and attachments

Treat recovered files like ordinary email attachments

Questions about this workflow

Is winmail.dat malware?

The container itself is a Microsoft email format, but any recovered attachment can carry the same risks as another email attachment.

How can a sender prevent it?

They can send internet-format HTML or plain-text mail instead of Outlook rich text, depending on their Outlook or Exchange configuration.