My German is not the best but I hope I understood right when I think you ask about how to insert images using Quicktext.
First I can say that it is possible. The thing you need to do is to add a normal image-tag:
<img src="http://example.com/image.gif">
You also need to under the template-field there is a select where you choose between insert template as Text or HTML. You need to set that to HTML.
If you want to insert local images that you want to be sent with the mail you just need to do:
<img src="file://C:\avatar.gif">
and the image is attached to the mail.
I hope I answered the right question 
If not someone else maybe have the answer or feel free to send a PM or email.