Buyer trust & fraud prevention

Easy path for real collectors, rising friction for bots and fraud rings — without making every Gmail user complete SMS and ID on day one.

Principle: friction grows with capability and risk, not with the signup form. Browse free → register light → verify email → bid → stronger checks at pay / elevated risk.

Legit buyer path (easy)

Step by step

Browse without an account
Register — email + password only (Gmail, Yahoo, iCloud, Outlook all fine)
Verify email — unlocks bidding for most people
Bid / offer on live lots
Win → save address + SMS phone before paying the seller
Larger or first-time card pays may show extra safety steps or a seller security hold

What we block at signup

Signal	Action
Disposable / temp email	Hard block
Honeypot field filled (bots)	Hard block (generic error)
IP registration flood (3+/hour)	Hard block temporarily
Form submitted in < ~1.5 seconds	Hard block (bot-speed)

What we flag (no block — more checks later)

Signal	Effect
Same device already used on other buyer accounts	Elevated risk · may require SMS before first bid
Same IP already has several accounts	Elevated risk · SMS-before-bid possible
Very fast form (but not bot-instant)	Soft score only
Odd email local-part patterns	Soft score only

Free webmail is not treated as fraud by itself.

Trust ladder (Account → Settings)

Browse freely
Verify email → bid (normal path)
SMS-verify phone → pay sellers / elevated accounts
Save shipping address → checkout
Trusted buyer → fewer holds as history builds

Payment-layer protection

Payments guide →

Already live

Phone + address gates before pay (by amount)
Card billing ZIP vs ship match; velocity limits
High-risk cards → security hold for seller release
High-value identity attestation for larger amounts
Local pickup distance check vs seller store ZIP

Seller view

On CDX Auction → Payments, sellers see risk badges, email verified, bill/ship notes, holds, and pickup distance. Release holds only when you accept the buyer.

After sale: tracking & claims

No automatic reship

A common fraud pattern is claiming not delivered or wrong item after a good sale. CDX treats that as high-risk by default.

Tracking required when marking a sale shipped
Shippo status refresh when the seller has a Shippo key
Buyers open structured claims under Account → Claims (must acknowledge: no automatic reship)
“Not received” after carrier Delivered is flagged for the seller
Sellers respond: deny (tracking delivered), request photos, or mark resolved — never auto-reship