In v16ce, I'm using an email template linked to an automation to send an email when when we change a field on Sales Orders. Currently the template email field is set to {{ object.partner_id.id }}. This only sends the email address associated with the customer. We'd like the email sent to all the stakeholders of a deal, i.e. the followers of the Sales Order. 

Is there an expression that would accomplish this? I've tried {{ object.message_follower_id.id }} with no success. Also, if there is more than one follower, would an expression still work of need a modifier? Suggestions would be greatly appreciated!