Do not re-subscribe updated email addresses by default

Imagine this scenario:

1. Person A is listed in your Marketo database as person.a@company.com.

2. Person A unsubscribes.

3. Company.com gets acquired; now all their emails are person.a@conglomo.com

4. You update Person A's email address to keep good hygiene--maybe sales will do a one on one email with them sometime.

5. Marketo sees the email address change and re-subscribes Person A.

While I would expect flags to be reset on say, invalid email, with an email address change, the Unsubscribe field is almost always used as a person-centric way of noting whether to mail someone or not. By resetting this field by default, you wind up emailing Person A when they've already told you they don't want to receive anything. Current Marketo behavior automatically re-subscribes the person and requires you to create a Smart Campaign to fix this. This should be the other way around; if you want to re-subscribe someone who's unsubscribed, you should have to do that through actions.

Please change this behavior so the record ​stays unsubscribed​.