When does a transactional email cross into marketing?

An order confirmation with a small "you might also like" section is still transactional. An order confirmation where the promotional content takes up more space than the order details probably isn't anymore. The test is: what's the primary purpose of this email?

CAN-SPAM defines it this way: if the "primary purpose" of the message is to advertise or promote a product or service, it's commercial. If it primarily contains transactional or relationship content, it's transactional. When an email contains both, the primary purpose test determines the classification. and that test looks at the content balance, subject line, and above-the-fold messaging.

A few scenarios that cross the line:

• An order confirmation where the promotional content (product recommendations, discount codes, newsletter sign-up prompts) occupies more space or visual weight than the order details
• A shipping notification with a prominent "while you wait, shop these items" section that functions as a mini-catalog
• A password reset email that includes a marketing banner or promotional footer that wasn't triggered by anything the user did
• A "your subscription has been renewed" email that includes aggressive upsell messaging for a premium tier

The fix is usually structural rather than legal. Move promotional content below the fold, after all the transactional information. Keep it proportionally small. Use a separate campaign for upsell messaging if you can. And if the email is primarily promotional but you're sending it because of a transaction, classify it as marketing and apply the appropriate consent and unsubscribe requirements.

The business risk of misclassifying: sending what regulators see as a marketing email to people who've unsubscribed from marketing, because you labeled it "transactional" to bypass suppression logic. See also consent requirements for transactional email.