[Evolution] evolution no background

[Tim <timh vivaldi net>]

Hello list

I hope someone can help me with Evolution 3.18.5.2 on Linuxmint 18.3

I need a background image in some of my mails. 
I tried first my own from ~/home then I tried Evo templates.
But every time before sending the image is gone only a background color
is possible.

What can I do?

thanks
Tim