Consider using Google's Guetzli Encoder when posting images. ;-)

 From:  amur (STEFAN) 1 Apr 2017  (7 of 10) 
8363.7 
Hi Pilou,

i wonder if you or anybody else can open also
my attachment without any problems. I used also
Google's Zopfli to compress the file instead
of .zip. Maybe i use it too in the future for
attachments if everybody can open it.

Zip file = 909.779 Byte
Zopfli = 895.999 Byte
some 3D doodles