SFMC Subscribers

Every successful marketing campaign starts with a subscriber—an entity who has given explicit consent to receive communication from your company. Whether you collect this information via online channels (like web sign-up forms capturing first name, last name, email, and age) or compliant offline channels (such as registration forms at restaurants or real estate agencies), you must follow proper anti-spam laws like CAN-SPAM before registering their data.

Once registered, Salesforce Marketing Cloud (SFMC) provides multiple ways to house this data. However, everything ultimately ties back to a single master database in Email Studio: The AllSubscribers list. Understanding how data flows into this central hub is crucial for any marketer.

        Subscriber Lists

SFMC allows you to group subscribers into standard lists, with a single list typically accommodating around 500,000 subscribers. The data flow here is direct and automatic:

• Any Personally Identifiable Information (PII) or profile data you add to a standard Subscriber List is instantlyand automaticallyadded to the master All Subscribers list.

        Data Extensions (DEs)

For more complex, contact-based data models, SFMC utilizes Data Extensions. Unlike standard lists, Data Extensions categorize information into two distinct functional buckets based on subscriber behavior and profiles:

• Sendable Data Extensions: These store a subscriber's PII/profile data (such as Subscriber Key, email address, and gender) used to route marketing communications. When creating a Sendable DE, you must define a Send Relationship, linking your custom fields to the master Subscriber Key in the All Subscribers list.


• Non-Sendable Data Extensions: These store behavioral or transactional details. For example, an e-commerce company needs to store invoice numbers, purchase history, bill amounts, or product specifications (color, size) post-purchase. By default, data extensions that are not explicitly marked as sendable become non-sendable, and their contents are never added to the master list.

Data Storage Comparison