How to Avoid Scams When Selling Online (2026 Seller Guide)

Published November 10, 2026 · By ListBomb

Short answer: keep every conversation and payment inside the marketplace, never send money back to a buyer, never share a verification code, and only hand over an item once real money is in your account or cash is in your hand. Almost every scam against sellers breaks one of those four rules.

Listing on more sites means more buyers, and also more messages from people who are not buyers at all. Here are the scams that show up most on resale sites, how to spot them, and what to do instead.

1. The overpayment

A "buyer" offers to pay by check or transfer, then sends more than your asking price with a story: a mover's fee, a shipping agent, a mistake. They ask you to send the difference back.

The FTC's guidance for sellers spells out how it ends: the check is counterfeit but good enough to fool a bank teller, it bounces after you have sent the money, and you are liable for the whole amount. The FTC's advice is simple. Don't accept a payment for more than your price, return it if the buyer won't correct it, and end the deal if they insist you wire money back.

Rule: you never send money to a buyer. Ever.

2. The verification code

Common on Facebook Marketplace and Craigslist. The buyer says they have been scammed before and want to "make sure you're real," so they will text you a code and ask you to read it back.

That code is Google sending a verification to your phone. State consumer officials, including Massachusetts, warn that the scammer uses it to create a Google Voice number linked to your phone number, which they can then use to hide their identity in other scams, or to try to get into your accounts.

Rule: never share any code you did not ask for. A real buyer has no reason to need one.

3. "Let's take this off the app"

A buyer asks for your email or phone number, or offers to pay by a method the site doesn't support. On shipping marketplaces this is the first step of most scams.

eBay does not allow offers to buy or sell outside eBay or sharing contact details before a sale is completed, and those deals are not covered by eBay's protection programs.
Mercari says it cannot resolve problems with offline transactions, and asks you to refuse and report anyone who asks to pay outside the app.
OfferUp recommends keeping communication in OfferUp messaging rather than sharing your phone number, email or address.

Rule: keep messages and payment where the listing is. On local sites, chat in the app until you meet.

4. Fake payment screenshots and fake "marketplace" emails

A buyer sends a screenshot of a payment app, or an email that looks like it came from the marketplace saying the money is "on hold" until you ship or click a link.

A screenshot is a picture, not money. eBay says phishing messages typically ask for confidential information, use an urgent or threatening tone, and link to a lookalike site, and that it keeps a copy of important messages in eBay Messages. Mercari says it only emails from @mercari.com, never sends links to outside sites, and never contacts you through chat messages.

Rule: check your balance in the real app or bank, opened yourself, not through a link. If the money isn't there, the sale didn't happen.

5. Unsafe local meetups

For in-person sales, the risk is to you, not just your money. OfferUp's safety tips recommend meeting in a busy, well-lit public place, preferably in daylight during business hours, bringing a friend or telling someone where you are going, and turning down last-minute requests to move to a different location. Facebook lets you create a meetup plan in Messenger and share it with a friend.

For payment, OfferUp recommends sellers accept only cash in person and avoid checks, gift cards, wire transfers and cryptocurrency; payment apps are safer than checks but still carry risk. Agree on the method before you meet.

Selling in Southern Nevada? See our Las Vegas local selling guide for police lots that double as safe exchange spots.

Red flags at a glance

Offers to pay more than your price, or to send a "courier" for the item
Requests for a code, your email, phone number or bank details
Pressure to ship before the payment shows in your account
A payment screenshot instead of real money
Links that ask you to sign in, sent by a buyer or a lookalike email
A last-minute change of meetup spot
A long sob story and a rush to close today

If something already went wrong

Stop replying, don't send anything else, and contact your bank or payment app right away. Report the account through the marketplace's own report tools, and report the scam to the FTC at ReportFraud.ftc.gov. If you shared a Google Voice code, follow Google's steps to reclaim your number.

Where ListBomb fits

ListBomb helps you write one listing from your photos and get it onto several marketplaces. It doesn't take payments from buyers: each sale is paid through the marketplace or in person, so that site's payment rules and protections apply. ListBomb posts to eBay through eBay's official API and to the free ListBomb Marketplace. For Facebook Marketplace, OfferUp, Craigslist, Mercari and Poshmark, it copies your listing text so you can paste it and tap Post yourself.

Free covers 2 items at a time, and Basic is $9.99/mo and Pro is $19.99/mo (yearly saves 10%). For listing tips, see how to crosslist items and how to delist sold items across marketplaces.

The short version: real buyers pay through the site or hand you cash. Anyone who needs you to do something else is the scam.

FAQ

What is the most common scam against online sellers?

Fake payments. A buyer sends a check or transfer for more than your price and asks you to send back the difference, or shows a screenshot of a payment that never arrived. The FTC warns that overpayment checks are counterfeit and bounce after you send money back, leaving you liable for the full amount. Only hand over the item once the right amount is in your own account or in your hand as cash.

Why does a buyer want me to send them a verification code?

It is a scam every time. The fake buyer says they want to confirm you are a real person, then asks you to read back a code texted to your phone. That code lets them set up a Google Voice number or open an account tied to your phone number. Never share a code you did not request.

Is it safe to take payment outside eBay or Mercari?

No. eBay does not allow buying or selling outside eBay, and those sales lose eBay's protection programs. Mercari says it cannot resolve problems with offline transactions and asks members to refuse and report requests to pay outside the app. Keep messages and payment inside the marketplace.

What payment should I accept for a local pickup sale?

OfferUp recommends sellers accept only cash for in-person sales and avoid checks, gift cards, wire transfers and cryptocurrency. Payment apps are safer than checks but still carry risk, so agree on the method before you meet and confirm the money has landed in your own app, not a screenshot.

How can I tell if a marketplace email is fake?

Phishing messages use urgent language, ask for passwords or bank details, or link to a lookalike sign-in page. Mercari says it only emails from @mercari.com and never messages you in chat, and eBay keeps a copy of important messages in eBay Messages. Open the app directly instead of clicking the link.

Does ListBomb handle payments from buyers?

No. ListBomb helps you create a listing and post it to several marketplaces, and each sale is paid through that marketplace or in person, so the marketplace's own payment rules and protections apply. ListBomb posts to eBay through eBay's official API and to the free ListBomb Marketplace; for Facebook Marketplace, OfferUp, Craigslist, Mercari and Poshmark it copies your listing text and you tap Post yourself.