Email picture not displayed when emailing direct from client

The header image is not displayed when emailing lists e.g. via email client has the troop track header. It reverts to the default TT image.

Emailing same group from TT web client the email does have the custom header under edit your email header image under TT settings. Has Custom image as expected.

I am getting the following when I send through my Outlook desktop client:

Am I doing something wrong?