Northern Trail Outfitters (NTO) plans on sending SMS and push notifications together with emails as part of a new customer onboarding journey. What…

For multi-channel communication involving email, SMS, and push notifications, the best practice is to use a channel-agnostic, unique identifier as the Contact Key. A GUID or another system-generated ID (like a Salesforce CRM Contact ID) is ideal. This ensures a single, stable identifier for each contact, regardless of whether their email address or phone number changes. It prevents duplicate contacts and allows for a unified view of the customer across all Marketing Cloud channels, which is essential for creating cohesive customer journeys.

A. A physical address is not unique to an individual and is unsuitable as a primary key for a contact record.

B. A phone number can be reassigned to a different person or shared, making it an unreliable unique identifier for a contact over time.

C. An email address is channel-specific and not suitable for contacts who may only engage via SMS or push; a person can also have multiple email addresses.

1. Salesforce Help, Contact Key. States, "The contact key is a unique identifier that you assign to a contact... Use the contact key to assign a single, unique identifier to a contact as they interact with your brand across different channels."

2. Salesforce Help, Subscriber Key. While specific to the Email Studio context, the principle is identical for the broader Contact Key. It recommends, "We recommend that you use a single, unique value for the subscriber key, such as a GUID or the 15- or 18-digit Salesforce contact, lead, or user ID."

3. Salesforce Help, Contacts Definition. Explains that a contact is an individual person in the Marketing Cloud database, identified by a unique Contact Key, and can be part of multiple channels.