Thank you for contacting Linnworks Technical Support.
I looked in your dispatch notification email settings and they look fine except Source='EBAY0'. EBAY0 is a subsource not a Source. I have disabled that template for now as it will not apply to any order.
Can you please try to disable the default template and then process a new order and check if it will work fine or not.
You can also try settings up the email notifications in Linnworks.net which is much more advance and you do not need to click on Send Selected all the time.
Please feel free to ask any further questions.