How Can I Force A New Mail Message To Be Plain Text Using The Mailto: Uri?

Using notification emails as part of a workflow. The notification contains action buttons are mailto: links that generate a message for the notified user to send their preferred ac

Solution 1:

No.

Nothing in the protocol allows you to suggest the content-type of the email created.

The user agent interpreting a mailto URL SHOULD choose not to create a message if any of the headers are considered dangerous; it may also choose to create a message with only a subset of the headers given in the URL. Only the Subject, Keywords, and Body headers are believed to be both safe and useful.