The marketplace's incentive is to keep the buyer, not hand them to you
On any marketplace, the platform is closer to a landlord than an ally when it comes to the next order. Order data, in-platform messaging, and repeat-purchase intent all stay inside the platform's own reach, feeding its own ad inventory and its own recommendation engine — not yours.
Every marketplace's seller terms treat direct diversion — pushing a buyer to contact you off-platform, quoting a lower price elsewhere, or routing a repeat order around the platform — as a policy violation, not a gray area. Get caught doing it inside checkout or on-platform chat, and the usual consequence is an account warning or a suspension, not a shrug.
None of that makes the relationship unreachable. It means the channels that are actually safe are narrower than most sellers assume, and they only hold up when treated as service touchpoints, not sales pitches.
The package insert: framed as service, it survives; framed as a pitch, it doesn't
A card inside the box is the one touchpoint a marketplace genuinely can't inspect before it ships — but that isn't a free pass. A card offering a discount code for your own site, or telling the buyer to 'order direct next time,' is exactly the diversion language that gets accounts flagged once a spot-check or a competitor's complaint catches it.
What tends to survive: a card built entirely around after-sales service — a warranty-registration QR code, a setup guide, a support contact for defect claims. None of it references price, none of it asks for a repeat order, and all of it gives you a legitimate reason to collect a phone number or a channel handle.
The QR code has to land somewhere that matches the card's framing. A 'register your warranty' code that opens a promotional sign-up page breaks the story the moment the buyer scans it, and hands the platform an easy screenshot if anyone ever complains.
- Warranty registration, not a discount code
- A support contact, not a repeat-order pitch
- The landing page has to match the card's framing
The after-sales conversation is where most sellers actually get caught
Once an order ships, some sellers treat the in-platform chat thread as an opening to pitch a repeat purchase or drop an external link. That's backwards — on-platform messaging is usually the most closely policed channel a seller has, not the least, because it's the one channel the platform can scan automatically for exactly this pattern.
The safer version of this conversation happens after delivery, is triggered by a real service need — a sizing question, a defect report, a how-to-use message — and only asks for permission to keep helping, not to sell again. 'Want the setup video sent over?' earns a yes far more often, and far more safely, than a store link.
The line to hold: everything inside on-platform chat should read like customer service, because it's being read by the platform the same way.
The delivery moment is your best shot at a real opt-in
The moment a buyer opens the box is the highest-trust point in the whole relationship — the product just arrived, it matches what they expected, and they haven't had time to get annoyed by anything yet. That's when the warranty card, or a follow-up message a day or two after delivery, actually gets read instead of ignored.
This is also where the opt-in has to be explicit, not implied. Scanning a QR code to register a warranty is not the same as agreeing to promotional messages, and treating it as one invites both a policy complaint and an annoyed unsubscribe. Ask separately, and make the second ask — hearing about restocks and new arrivals — a clear yes or no, not a default.
Once that separate yes exists, the contact has genuinely left the marketplace's reach and landed on a list you operate, message, and own — which is the entire point of the exercise.
What actually triggers account-level trouble
The common thread across marketplace enforcement isn't that a seller built an owned list — it's that they used marketplace-owned surfaces, like checkout notes, on-platform chat, or packaging, to sell around the platform instead of after it. Price comparisons, links to 'buy again cheaper,' and coupon codes tied to a competing storefront are the patterns that get flagged fastest, because they're also the ones that cost the platform its commission directly.
Everything in this piece works precisely because it avoids that pattern — it asks for permission to serve, not permission to sell, and it waits until after delivery to do it. Per the seller terms most marketplaces publish, that's the difference between a warranty card and a policy violation carrying the same QR code.

