Dear Rolf HV Gustafsson,
Sincere apologies for misunderstanding you!
As far as I am concerned, the function you are referring to is the mailto link. To achieve your need, you may try using a mailto link with both the subject and body parameters. Here is the format you can use:
mailto:your.email@example.com?subject=Your%20Pre-filled%20Subject&body=Your%20Pre-filled%20Content
When someone clicks on this link, it will open a new email window in their Outlook with the subject line and content pre-filled with "Your Pre-filled Subject" and "Your Pre-filled Content" respectively.
If you want to pre-fill a multiple line body in an email, you can use the %0A (newline) character to create line breaks in the body of the email. Here is an example of how you can format the mailto link:
mailto:your.email@example.com?subject=Your%20Pre-filled%20Subject&body=Line%201%0ALine%202%0ALine%203
When someone clicks on this link, it will open a new email window in their Outlook with the subject line pre-filled with "Your Pre-filled Subject" and the body content pre-filled with:
Line 1
Line 2
Line 3
For more info, please kindly refer to Add a return email (mailto:) link in a message - Microsoft Support.
Appreciate your patience and understanding and thank you for your time and cooperation. I wish you all the best!