Northern Trail Outfitters (NTO) uses data extensions for all of their email audiences. A customer reports they unsubscribed several week-end ago, but continue to receive NTO's daily digest at their old address. NTO's Marketing cloud Admin has confidently deleted them from present in the appropriate data extension.
What consideration could account for this behavior?

NTO has been noting reduced deliverability when they do large sends.
Which part of deliverability is tied to hitting Spam Traps during a send?

Northern Trail Outfitters wants to optimize their eCommerce site by sending a follow-up Email to a customer alter an online purchase is made.
What feature could be used to solicit website feedback without navigating away from the email?

Northern Trail Outfitters needs to reduce the amount of work when managing messages to customers, but cannot add any more personnel due to budget constraints. There has been an increased number of customer purchases on their website, and the team currently sends batch order confirmations. What solution will decrease manual workloads on the team and will improve their customers experience?

A Marketing Cloud admin wants to check the status of a salesforce contacts in All Subscribers. The account is connected to their salesforce org via Marketing Cloud Connect.
Which subscriber key should be used to search for the contact in All Subscribers?