Typically, Outlook may occasionally convert attachments into 'winmail.dat'.
This situation commonly arises when the email client sends emails formatted in Rich Text, such as bold, italics, and so on.
The formatting details are embedded within the winmail.dat file, which may be treated as an attachment by the recipient's email client. Additionally, other standard file attachments can also be saved as winmail.dat files.
Here’s a brief guide on how to prevent this issue from occurring.
- Launch your Outlook email client.
- Click on File in the top toolbar.
- Choose the Options setting.
- Then, select the Mail category.
- Next, under Compose messages, make sure to select either HTML or Plain Text for Compose messages in this format.
- After that, in the Message format section, change When sending messages in Rich Text format to Internet recipients to Convert to HTML format or Plain Text format
- Finally, click OK to complete the process.