Thanks a lot for your fast reply.
In my case the header is "X-AMAZON-MAIL-RELAY-TYPE" which is the last of your list.
So it will prevent OOF in case the customer from Amazon has set it inside Amazon, understand.
But theoretically i could also delete the line
X-AMAZON-MAIL-RELAY-TYPE' => 'NOTIFICATION',
from the class.filter.php file, correct?
The problem is, that if the ticket does not reopen, then the answer to the Amazon customer will not be on time since Amazon wants you to answer within 24h if possible. But checking on Seller Central each day if someone wrote anything is also a little stupid.
If I don't use auto reply messages for Emails coming from Amazon, then this should be ok i guess. This way there should normally also not be any OOF problem!?