[Mailman-Users] Cleaning up email headers

[TheClarkes]

I am a ceramic artist living in Eugene, OR. My mailing list of 
customers is now done with mailman.
However, I notice that the email headers are crammed with extraneous 
information/lines.
Despite my best efforts to reduce the header clutter, I'm still left 
with unwanted lines (see below in boxes)
[]

Does anyone know how to reduce the header further ? I'd love to get 
it to something simpler and less intrusive ...
thanks ... don