Winmail.dat

The infamous "winmail.dat" file!

"Winmail.dat" is a file that is often generated by Microsoft Outlook when it is configured to use a proprietary format for sending emails with attachments. This format is called "TNEF" (Transport Neutral Encapsulation Format).

When you send an email with an attachment from Outlook, it converts the attachment into a TNEF file and saves it as "winmail.dat" in the email body. This file contains the attachment, as well as other information such as the email headers and body.

The problem is that not all email clients can read TNEF files, which can cause issues when trying to open or forward the email. This is because TNEF is a proprietary format that is specific to Microsoft Outlook.

Here are some common issues that can occur when dealing with "winmail.dat" files:

  1. Attachments are not visible: When you receive an email with a "winmail.dat" attachment, you may not be able to see the attachment in your email client. This is because the attachment is stored in the TNEF file, which may not be readable by your email client.
  2. Attachments are corrupted: When you try to open or forward an email with a "winmail.dat" attachment, the attachment may become corrupted or lost. This is because the TNEF file is not compatible with all email clients.
  3. Email clients may not support TNEF: Some email clients, such as Gmail or Yahoo Mail, may not support TNEF files. This means that you may not be able to open or forward emails with "winmail.dat" attachments.

To avoid these issues, you can try the following:

  1. Use a different email client: If you're using Outlook, try using a different email client that supports TNEF files, such as Microsoft Exchange.
  2. Convert TNEF files to a standard format: You can use a third-party tool to convert TNEF files to a standard format, such as PDF or ZIP.
  3. Ask the sender to resend the email: If you're having trouble opening or forwarding an email with a "winmail.dat" attachment, you can ask the sender to resend the email in a standard format.

Overall, "winmail.dat" files can be a nuisance, but there are ways to work around the issues they cause.