Hi Jetze,  Nice idea to help automate and maintain consistency in your application.   Try using either a text box or the Rich Text Editor editor to present the initial info to the user.  Using standard pega  flow and UI to present the prefilled info would work, then when they submit move to a utility shape that sends the email.  However if you have more complicated requirements, (IE do you want HTML email, PDF, plain text etc) I would review the pages starting at this landing page for additional ideas...
https://pdn.pega.com/correspondence