Marketing consent rules: email vs. physical mail, explained simply

The rules for contacting customers differ sharply by channel, and the difference is worth understanding precisely — it changes who you can reach. The short version: marketing email requires consent; postal mail to your own customers does not. Here’s the longer version, in plain English. (Plain English, not legal advice — rules vary by country and change; when stakes are high, ask a professional.)

Email: consent-first, always

• Consent is recorded, not assumed. Buying from you does not opt a customer into marketing. The checkout checkbox does, and Shopify stores that flag per customer (accepts marketing). Good tools check it at send time — every time — because consent can be withdrawn between sends.
• Unsubscribe must be easy and honored fast. One step, no login, no “are you sure.” Once someone unsubscribes they go on a suppression list that outranks every campaign and automation you’ll ever configure.
• Transactional email is different. Receipts and shipping notices don’t need marketing consent — but stuffing promotions into them converts them, in spirit and eventually in enforcement, into marketing.

Postal mail: permitted, with manners

In the US there is no opt-in requirement for sending marketing mail to your own customers — the address on their order is enough. That single fact is why direct mail reaches the customers email cannot: the never-consented, the unsubscribed, the dead-inbox. The obligations that do exist are practical ones:

• A real return address on every piece — postal regulations expect it, and it’s where undeliverable mail comes home.
• A respected do-not-mail list. No statute forces the American version, but the first “please stop” you ignore costs more goodwill than a thousand cards earn.
• Restraint as strategy. Mail works because mailboxes are quiet. The channel rewards stores that treat a card as an occasion (a high-LTV customer going quiet, a run-out approaching) and punishes weekly wallpaper.

The channel-choice consequence

Put the two rule sets together and a sensible contact policy writes itself: email first where you have consent (free, instant, reversible), mail where you don’t or where email went unanswered (no consent barrier, higher attention, real cost per piece). That’s not a legal workaround — it’s using each channel exactly as its rules intend, and it’s the shape of every good reorder program’s ladder.

What your tooling should guarantee

You shouldn’t be enforcing any of this by hand. The checklist for any app that contacts customers for you: consent checked at send time, one-click unsubscribe headers on every marketing email, a suppression list that wins every conflict, per-product opt-outs where they make sense, and — on the billing side — caps that make runaway anything impossible.