How to Stop Outlook from Sending Winmail.dat Attachments

Have you ever sent an email, only for the recipient to send a reply telling you that they can't open the Winmail.dat attachment file you sent them? And you're probably wondering what they're referring to as you've never sent them such a thing right? Well if this sounds familiar, then don't worry as you're not alone and we have the solution.

What exactly is the Winmail.dat file?

A winmail.dat file is a file containing information sent with a Microsoft Outlook email which allows it to retain all its files, fonts and format. If the recipient is also using Outlook, this file can be automatically decoded, if not, the winmail.dat file will appear in addition to your message, but often ruining the included files, font styling and formatting.

The winmail.dat file is almost always generated when Outlook is sending your emails in Rich Text Format (RTF) which other email clients don't support. By changing your Outlook settings, you'll be able to prevent Outlook from sending this pesky file. you'll

How do I prevent my Outlook from sending Winmail.dat files?

There's two causes to your Outlook sending Winmail.dat files. The first is that your settings are set to send emails in Rich Text Format, which you can change with the following steps:

1. Click File in Outlook.
2. Select Options.
3. Go to the Mail tab.
4. Make sure HTML or Plain Text is selected for Compose messages in this format: under Compose messages.
5. Now make sure Convert to HTML format or Convert to Plain Text format is selected for When sending messages in Rich Text format to Internet recipients: under Message format.
6. Click OK.

The second cause is because your saved contacts have their own specific settings which will often override your Outlook settings. You will need to delete your saved contacts if you're experiencing this issue with them.

If you're experiencing this issue with specific recipients who aren't a saved contact, you can follow these steps to manually alter the sending preferences:

1. Open an email from the desired recipient or compose a new email to them.
2. Click on the email address with the right mouse button.
3. Select Outlook Properties… from the menu that appears.
4. Make sure either Let Outlook decide the best sending format or Send Plain Text only is selected under Internet format:.

Is it possible to open the Winmail.dat file?

Yes it is. You can view or open a winmail.dat file by downloading third-party software such as a winmail.dat decoder.