How to change the request template for sending emails from the request profile?

When a mail is sent from a request profile, this is done using a predefined format. How to change this format?

The format is determined by a system defined email template and system defined email templates cannot be edited in system manager.

As a workaround, it is possible to change the message text directly in the database, but the number and the position of the parameters must remain the same, or the outcome will be an incorrect mail.