You list a jacket on a Tuesday and it sells within the hour. The buyer messages you almost immediately: could you ship today, and could you message them on WhatsApp so they can send the address? It feels like a lucky break. It is also the opening move of one of the most common seller scams.
Most scams aimed at new sellers share a small set of patterns. This guide sticks to what eBay, Poshmark, Mercari, the FTC, and the FBI publish about them, and it separates that from what sellers report but the platforms have not confirmed.
The Pattern Behind Most Scams: Leaving the Platform
The simplest warning sign is a request to move the conversation or the payment somewhere else. The platforms all say the same thing about it:
- eBay: "Due to potential for fraud, we don't allow buyers and sellers to complete sales outside of eBay." (eBay Security Center)
- Poshmark: sales that start on Poshmark must be completed on Poshmark, and the community guidelines say Posh Protect does not cover a transaction if any part of it was taken off the platform.
- Mercari: its help center tells users to avoid requests to communicate or conduct transactions outside Mercari, and says it cannot protect you if you move outside its secure environment.
Etsy's seller policy likewise prohibits steering buyers to pay off-platform, and Depop's safety pages tell users to keep chatting and paying in the app. The practical rule: if anyone asks for your phone number, a payment app, or a chat on another service before the sale completes, decline and keep it on the platform. You lose your seller protection the moment you leave.
Overpayment and Fake Check Scams
This one has been around for years and still works on new sellers. A buyer pays more than your price, or sends a check for too much, then asks you to send back the difference, sometimes to a third party.
eBay says to never accept overpayments from buyers, noting that requests like this are often part of a counterfeit cashier's check scheme. The FTC explains why it works in its guidance for people selling online: a bank may make a deposited check available within about two days, but "it can take weeks for the bank to figure out the check was fake." By then you have sent the "refund," and the check bounces. Its rules for sellers are simple: never deposit a check for more than the selling price, and do not accept a mobile payment from someone you do not know. The FTC's fake check guide describes the overpayment version directly.
Fake Payment Confirmations and Pressure to Ship
A real payment shows up in your account on the platform. A scam shows up in your inbox. The FBI's Internet Crime Complaint Center lists these red flags for sellers in a November 2023 advisory:
- A buyer who overpays and wants the difference sent to a third party
- An email that looks like it came from a payment or money transfer company saying the buyer has sent funds, when you have not confirmed receipt yourself
- A buyer pressing you to ship right away, or to ship before the payment arrives
The defense is to ignore the email and check your own account. On eBay, Etsy, Poshmark, Mercari, and Depop, you get paid through the platform, and the platform's own record of the sale is the only one that matters. Do not ship until the platform tells you to.
Phishing and Impersonation
Scammers also pretend to be the marketplace itself, with an email that claims your account needs "verification" or a sale needs confirming, and a link to a page that collects your login.
- eBay: if a message claims to be from eBay, sign in to My eBay and check Messages. If it is not there, it is not from eBay. eBay's Security Center says to forward suspicious emails to spoof@ebay.com.
- Mercari: says it never sends links to external sites, and that its email comes only from addresses ending in @mercari.com. Forward suspected phishing to the address on its phishing page and log in only through the app or by typing the web address.
- Etsy and Poshmark: each has a help-center page for reporting phishing, and Depop has a Safety Centre. Open them from inside your account rather than from a link in the message.
Never click a link in an unexpected email. Type the site address yourself.
Item-Not-as-Described and Return Claims
Not every bad outcome is a scam, but a false "not as described" claim or a return that comes back empty or with the wrong item can cost you the same money. Each platform's seller-protection page describes what it covers, and the rules differ, so read the one for the platform you sell on:
Photograph the item and the packaging before you ship, and keep the tracking number. That evidence is what these protections rely on. We could not confirm equivalent official pages for Etsy, Mercari, and Depop on this specific kind of dispute, so check each platform's help center.
What Sellers Report That the Platforms Haven't Confirmed
These show up repeatedly in seller forums and security blogs, but we could not find an official platform page that names them, so treat them as reports, not documented facts:
- Buyers asking you to ship to an address other than the one on the order
- Fake "payment received" emails that appear to come from your own email address
- Fake "support" messages inside a marketplace's chat asking for your email or bank details
- QR codes in messages that lead to phishing pages
- Scam messages arriving within hours of opening a new shop
The defense against all of them is the same as above: keep the sale on the platform, ship only to the order's address, and trust only what your account shows.
If You Think You've Been Scammed
- Stop communicating with the buyer and do not send more money or items.
- Report it to the platform from inside your account.
- File a report with the FTC at reportfraud.ftc.gov. For internet-related fraud, the FBI also takes reports at ic3.gov.
- Contact your bank right away if you deposited a check or sent a payment.
Keep Personal Details Out of Your Shop Name
New sellers are often targeted because shops are easy to find. A shop name that uses your real name or location gives a scammer more to work with. Our guide to anonymous reseller usernames covers picking one that doesn't, and you can confirm a name is free on every platform you use with the username checker.
Where This Guide Stops
Platform policies change, and scammers change tactics faster than help pages are updated. This is not legal or financial advice. The links above go to the sources, which are more current than any summary. When a request feels wrong, the platform's own policy usually already says why.
Frequently Asked Questions
Can I lose money if a buyer overpays and asks me to refund the difference?
Yes. The FTC says that a buyer who sends a check for too much and asks for the balance back is running a scam. A bank may make the funds available within days, but it can take weeks to discover the check is fake, and by then you have sent real money and often the item.
What should I do if a buyer asks me to pay or chat outside the platform?
Decline and keep everything on the platform. eBay, Poshmark, and Mercari all prohibit completing sales outside their platforms, and each says its seller protections do not cover a transaction that moved off-platform.
How do I know if a message from a marketplace is real?
Check inside your account instead of trusting the email. eBay says a real message will also appear in your My eBay Messages, and Mercari says it never sends links to external sites and only emails from addresses ending in @mercari.com.
Where do I report a seller scam?
Report it to the platform first, then to the FTC at reportfraud.ftc.gov. For internet-related fraud, the FBI also takes reports at ic3.gov.
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