How do i prevent emails being sent when a delivery note is updated ?
there is no such standard process which automatically send email when delivery note is updated, please check your implemenation there must be some setup for that.
most probably you check document print management setup
If this post helps you, Please verify this answer and earn Thank you Badge for yourself (Follow this link for more details https://community.dynamics.com/braggerbadges/badge/48.aspx)
Do you have an Email notification batch running?
Check the batch and remove the condition for the delivery update notification