Northern Trail Outfitters received a complaint today from a customer who received an email after...

When Email Address is used as the Subscriber Key, unsubscribe status is tied to that specific address value rather than to a stable, unique identifier. If the automation-driven, file-based send last week processed the unsubscribe against a subscriber record keyed by email address, but MCC ' s own record-matching and opt-out logic resolves identity differently (for example, against ContactID or a separate Subscriber Key structure), a mismatch between how the two send pathways identify ' the same person ' can result in the unsubscribe not being recognized when Marketing Cloud Connect later sends to that same individual — effectively creating two disconnected identity records for opt-out purposes. This is a classic, documented pitfall of using Email Address as Subscriber Key in environments where both native Marketing Cloud sends and Marketing Cloud Connect sends coexist. Option B is inaccurate — Email Opt Out status is not gated by whether a send ' originates in Salesforce ' ; it is a subscriber/contact-level status. Option C, adding a field to a page layout, is a UI-visibility concern with no bearing on whether opt-out logic is honored at send time. Option D, edit permissions, would affect the user ' s ability to configure the send, not whether unsubscribe status is respected. Reference: Subscriber Key Best Practices, Marketing Cloud Connect Opt-Out Handling.