Mark email as read if it is moved to trash
One solution could be as follows: 


In Macbook, create an Apple script that uploads new emails and marks emails in a given folder as read:

tell application "Mail"
check for new mail
set read status of messages of mailbox "Deleted Items" of account "XXX" to true
end tell



Note that emails that are deleted on iphone do not end up in the Trash but Deleted Items folder in the Mail app on Macbook.


Using the inbuilt Automator on Macbook, create and store an .app that executes the above script.
Use freeware ControlPlane to run the above app upon each log-in. I allowed for a time lag of 10 seconds for the Macbook to establish Internet connection before the app is executed.