There are 2 possibilities to entertain in mailing preferences as highlighted in the image below;
Now as per Option 1, where the lead individually chooses the kind of emails they must receive, please view the below behavior outcomes:
Step 1: Check the required outreach types (or) uncheck the type of emails you would not like to receive.
Step 2: Hit Submit.
And voila, the below is the Outcome on the platform;
Kindly note that "Do Not Email" will be marked as "No" for this even if the lead unchecks all email types in the email preferences. So whitelisting is not required here.
Now as per Option 2, if the lead marks "Unsubscribe from all", the outcome is considerably different;
Step 1: Hit Unsubscribe from all
Step 2: The lead must choose a particular reason.
And now onto the Outcome, we can see that this marks them as Do Not Email to "Yes".
Now on the eventuality that the lead chooses "Option 2", but later chooses to "Re-Subscribe" via Mailing Preferences, this will automatically flag the "Do Not Email" back to "No".
Having presented the 2 possible outcomes, please note that the requirement to whitelist an email address from a suppression list via our email experts is only required when the lead goes to "Do Not Email" marked as "Yes" and over the course of time chooses to "Re-Subscribe" back.
Hope this addresses your queries :)