How to Prevent Winmail.dat Attachment in Outlook

Content
  1. How to avoid those annoying Winmail.dat attachment?
  2. When, how and why was Winmail.dat created
  3. Prevent Winmail.dat attachments from being sent to Outlook
  4. Preventing Winmail.dat attachments in Outlook 2007 and Outlook 2003
  5. Disable Winmail.dat for specific recipients
  6. In Outlook 2019 and 2016
  7. In Outlook 2013, 2010 and 2007
  8. Extract files from Winmail.dat without Outlook

How to avoid those annoying Winmail.dat attachment?

Are your recipients complaining about a mysterious attachment called winmail.dat that they can’t open? Do files you attach to emails disappear into that abyss of winmail.dat? Does Winmail.dat appear for some but not all recipients of your messages? Fortunately, you can completely remove winmail.dat by stopping Outlook from sending email in rich text.

The instructions in this article apply to Outlook 2019, 2016, 2013, 2010, 2007, 2003; and Outlook for Office 365.

When, how and why was Winmail.dat created

When Outlook sends a message with rich text for bold text and other text enhancements, it includes the formatting commands in the winmail.dat file. When receiving email clients that do not understand this code, it will be displayed as an attachment. Outlook may also package other attachments in the winmail.dat file.

Prevent Winmail.dat attachments from being sent to Outlook

To prevent Outlook from attaching the winmail.dat file when sending email:

  1. Go to File

  2. Select parameters:

  3. Go to mail

  4. In chapter Create messages select drop-down arrow Create posts in this format and choose HTML or flat text † †

  5. In chapter Message format select drop-down arrow When sending rich text messages to Internet recipients and choose Convert to HTML Format or Convert to plain text

  6. Select Okay

Preventing Winmail.dat attachments in Outlook 2007 and Outlook 2003

To prevent Outlook 2007 from adding winmail.dat files to Outlook 2003:

  1. Select Tools parameters:

  2. Go to Email Format

  3. In chapter Create posts in this format select HTML or flat text

  4. Click Okay

Disable Winmail.dat for specific recipients

The default outgoing email format settings in Outlook can be overridden for an individual email address. If the recipient still receives a winmail.dat attachment after you change the settings, reset the format for individual addresses.

In Outlook 2019 and 2016

  1. Make sure the email address isn’t in your Outlook contacts.

    In Outlook 2019 and 2016, there is currently no way to change the sending settings for email addresses assigned to an address book entry.

  2. Open an email from the desired email address or create a new message for it.

  3. Right click on the address.

  4. Select Open Outlook Properties

  5. In chapter internet format select Send plain text only

  6. Select Okay

In Outlook 2013, 2010 and 2007

  1. Find the desired contact in your Outlook contacts.

  2. Double-click the contact’s email address or right-click the desired email address, then select Open Outlook Properties or Outlook properties

  3. In chapter internet format select Let Outlook choose the best sending format or Send plain text only

  4. Click Okay

Extract files from Winmail.dat without Outlook

If you receive winmail.dat attachments with embedded files, decompress them using the winmail.dat decoder on Windows or OS X.

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