Yes, it will apply the Email Address Policy automatically once the object is modified and saved:
https://video2.skills-academy.com/en-us/exchange/email-address-policies-exchange-2013-help
Each time a recipient object is modified and saved, Exchange enforces the correct application of the email address criteria and settings. When an email address policy is modified and saved, all associated recipients are updated with the change. In addition, if a recipient object is modified, that recipient's email address policy membership is reevaluated and enforced.