Click the "Select File" button above, and choose your TNEF file.
You’ll see a preview, if available.
Click the "Convert file to..." button to extract text information.
Convert TNEF to another file type
To convert TNEF files to another format, you need Microsoft Outlook or other Encoded software.
Convert a file to TNEF
To convert other file formats to the "Email Encapsulation Format" file type, you need software like Microsoft Outlook or a similar tool.
About TNEF files
A .tnef (Transport Neutral Encapsulation Format) file is a proprietary email attachment wrapper created by Microsoft. It is primarily generated by Microsoft Outlook and Microsoft Exchange Server to package rich-text formatting, embedded objects, and standard attachments into a single data stream. These files typically arrive in a recipient's inbox with the filename winmail.dat or win.dat. Microsoft Outlook reads these files natively, seamlessly decoding the contents so the user never even sees the .tnef wrapper. For more technical background, see the Transport Neutral Encapsulation Format Wikipedia page. The main disadvantage of the .tnef format is its strict vendor lock-in. Non-Microsoft email clients like Apple Mail or Mozilla Thunderbird cannot natively decode it. When users receive this file, they are entirely locked out of the email body text and the actual intended attachments. This causes significant frustration and productivity loss in mixed-platform environments. The best solution is to extract the .tnef contents rather than standard conversion. Converting the wrapper into an EML or MSG file allows standard email clients to read the original message structure. You can also extract the embedded payload directly, yielding the originally attached PDF, DOCX, or JPG files. Because this is a tightly closed, proprietary format, standard online image or document converters usually fail to process it. You need a dedicated extraction tool that understands the internal TNEF data structures. Just drag and drop your .tnef file into convert.guru to identify the format, view its structure, and extract or convert the embedded files when supported.
Convert.Guru analyzes your TNEF file, detects the exact format, and lets you read the text inside.
If you want to convert TNEF file to TMP, TEMP, CACHE, LOG, BAK, OLD, NEW, PART, DOWNLOAD, CRDOWNLOAD, LOCK or PID, you can use Microsoft Outlook or similar software from the "Email Encapsulation Attachment" category. In the File menu, look for Save As… or Export….
To convert DEVICE, CACHE, SOCK, SYMLINK, PID, MOUNT, FIFO, LOG, PIPE, TMP, JUNCTION or TEMP files to TNEF, try Microsoft Outlook or another comparable tool in the "Email Encapsulation Attachment" category.
The TNEF Converter Story
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our TNEF converter.