All message files for DirectAdmin are stored in /usr/local/directadmin/data/templates (check for .txt files). Copy them to folder "custom" and then edit them as you see fit.
You can also edit welcome message when you create new user.
I now
But my question is: HOW I CAN CHANGE HEADERS IN THIS MESSAGE.
I have file stored in utf8 (html), but mail clients not reading message properly.
Regards