When does a transactional email cross into marketing?

A transactional email crosses into marketing territory when promotional content becomes substantial enough to change the message's primary purpose. An order confirmation with a small "You might also like" product suggestion remains transactional. The upromotional element is secondary to the receipt function. But a shipping notification that's 80% promotional content with a brief shipment update buried at the bottom has functionally become a marketing email, regardless of what triggered it or how it's labeled in your ESP.

Regulators and ISPs apply a "primary purpose" test to evaluate mixed-content emails. Under CAN-SPAM, if the promotional content would lead a reasonable recipient to conclude that the message's primary purpose is commercial, it must comply with commercial email requirements-even if there's legitimate transactional content included. The FTC has provided guidance suggesting that if the subject line would lead recipients to think the message is commercial, or if promotional content appears first or is visually dominant, the message will be treated as commercial.

Specific elements that push a transactional email into marketing include: promotional content that takes up more space than transactional information, subject lines that emphasize promotions over the transaction, excessive product recommendations that dwarf the actual notification, and offers or calls-to-action that compete with or overshadow the transactional purpose. Best practice is to keep transactional emails focused-provide the necessary information clearly, and if you want to add promotional elements, keep them minimal and clearly secondary. The moment your "order confirmation" looks more like a sales pitch with a receipt attached, you've crossed the line into marketing.