Marketplace fraud prevention comes down to a few habits. If you are wondering how to prevent scams on a classifieds site, the short answer is: check new listings before or as they go live, keep messages and payments on your site, verify the sellers who carry the most risk, make it easy to report a listing and act on every report, and block bots and spam at sign-up. This guide covers the scams that hit classifieds and marketplaces most often, how owners detect and stop them, how to prevent fake profiles, and marketplace spam prevention. It is part of our guide to building trust in a marketplace.
Part of the guide Trust and safety for your marketplace · Part 3 of 8 Next: Marketplace Compliance: GDPR, DSA, Privacy and Security →
The scams that hit classifieds and marketplaces
Knowing what scams look like is the first step, because most of them follow a pattern you can screen for. These are the ones marketplace owners see most:
| Scam | How it works | Warning signs |
|---|---|---|
| Fake listings | A scammer posts an item, car or rental that doesn't exist or isn't theirs, often copied from a real listing with the contact details changed, and takes the money. | Price far below market, photos copied from elsewhere, a seller who can't show the item or meet in person. |
| Advance fees and deposits | The buyer is asked to pay a deposit, application fee, "shipping" or "insurance" before seeing the item. Rentals, pets, tickets and vehicles are common targets. | Pressure to pay before a viewing, urgency ("other people are interested"), a story about why the seller is away. |
| Overpayment and fake checks | A "buyer" sends a check or payment for more than the price and asks the seller to send back the difference. The payment later bounces, and the seller has lost the item and the refund. | An offer for more than the asking price, a check, a request to refund the extra by wire or gift card. |
| Fake payment notifications | A buyer insists on a payment app and sends a fake "payment received" email or screenshot, hoping the seller ships before checking. | A payment that shows in an email but not in the seller's own account. |
| Phishing links | Messages or listings link to fake login, payment or "delivery" pages that copy your site or a payment provider, to steal passwords and card details. | Links in messages, look-alike domains, requests to "confirm" an account or payment. |
| Verification code theft | A "buyer" asks the seller to read back a code sent by text, supposedly to prove they are real. The code lets the scammer take over an account or open one in the seller's name. | Any request to share a one-time code. |
| Payment off the platform | The other side asks to move the chat to another app and pay by bank transfer, gift card or crypto, outside any protection your site offers. | "Text me on WhatsApp", "my email is…", a refusal to use the site's checkout. |
| Account takeover | A criminal logs in to a real user's account with a stolen or guessed password and uses its good reputation to post fake listings or message buyers. | Sudden changes to an old account: new contact details, many new listings, unusual prices. |
| Fake profiles | Accounts created in bulk, often by bots, to post scam listings or spam and to come back after being blocked. | Disposable email addresses, many sign-ups from the same source, empty profiles that post straight away. |
| Non-delivery and return fraud | The buyer pays and nothing arrives, or a buyer claims an item never arrived (or returns a different one) to get a refund. | New accounts with high-value deals, repeated claims from the same user. |
Return and refund abuse is covered in more detail in our post on handling refunds and returns.
Marketplace fraud in numbers (as of October 2026)
Fraud figures quoted online often can't be traced to a real report. These are the most recent official numbers, published in 2025 and 2026:
| Source | Figure |
|---|---|
| FBI IC3 2025 Internet Crime Report | 1,008,597 complaints and $20.877 billion in reported losses in 2025, 26% more losses than in 2024. Non-payment/non-delivery: 56,478 complaints and $503.4 million lost (2024: $785.4 million). Phishing/spoofing losses rose from $70.0 million in 2024 to $215.8 million. Advance fee: 7,762 complaints, $155.9 million. Overpayment: 2,194 complaints, $22.9 million. |
| FTC, 25 March 2026 | 3 million fraud reports in 2025 with $15.9 billion in reported losses, up from 2.6 million reports and over $12 billion in 2024. |
| FTC, March 2025 | In 2024, people lost more to scams paid by bank transfer or cryptocurrency than by all other payment methods combined. Online shopping was the second most reported fraud category, and 38% of people who reported a fraud lost money (27% in 2023). |
| FTC Data Spotlight, 27 April 2026 | $2.1 billion lost in 2025 to scams that started on social media, about eight times the 2020 figure. Websites and apps were the most common starting point for people who lost money (31%), with social media close behind (nearly 30%). More than 40% of people who lost money to a social media scam said it started with something they ordered from an ad. |
| FTC Data Spotlight, 22 December 2025 | Nearly 65,000 rental scam reports and about $65 million lost from January 2020 to June 2025, with a median loss of $1,000. In the 12 months to June 2025, about half started with a fake Facebook listing and 16% with a fake Craigslist listing. |
| BBB 2025 Scam Tracker Risk Report | Online purchase scams rose to No. 3 on the riskiest list and made up 28.4% of published reports; 89.3% of the people who reported one lost money. PayPal was the organization scammers impersonated most often. |
The pattern is clear: simple non-delivery losses went down, phishing losses tripled, and the largest sums went through payments that are hard to reverse. Fake listings and "too good to be true" offers are still the main way in, so a classifieds site that covers housing, vehicles or goods has to deal with them.
How to prevent scams on a classifieds site
No single tool stops every scam. What works is a few layers, each catching what the one before missed. Start with the cheap, simple controls and add more as your site grows and your own reports show new patterns.
1. Decide how listings get published
The most effective check happens before a listing is visible. You can publish listings straight away, hold them for approval, wait until the seller confirms their email, or publish only after payment. Many owners mix these: new accounts' first listings and high-risk categories (rentals, pets, electronics, tickets, vehicles) wait for approval, while trusted sellers publish straight away. Paid listings also put off spammers, who rarely pay to post.
2. Screen every listing for scam patterns
Manual review doesn't scale, and scammers use bots and networks of fake accounts. Automated screening catches the obvious cases so your moderators can focus on the doubtful ones. Things worth checking automatically:
- Price: far below the usual price for the category.
- Text: banned words, requests for deposits, gift cards or wire transfers, contact details or external links in the description, urgency.
- Photos: images reused from other listings or from the web.
- Behaviour: a new account posting many listings at once, sudden changes to an old account, many accounts from the same source.
Where AI helps. Language models and machine learning can read a listing the way a moderator would and flag the ones that match known scam patterns, including new wording that a keyword list would miss. Behavioural models learn what "normal" looks like on your site and flag unusual activity. Two cautions: models trained on your own data need a history of confirmed fraud cases to learn from, and any automated system produces false positives. Hold risky listings for a person to review instead of deleting them, and record the reason, so you can explain the decision and correct mistakes.
| Challenge | What goes wrong | What to do |
|---|---|---|
| False positives | Genuine sellers get blocked and leave. | Hold for review instead of deleting; tell the seller why; let them appeal. |
| Explainability | Nobody can say why a listing was blocked. | Use tools that give a reason for each decision, and keep a log. |
| Not enough data | A small site has too few fraud cases to train a model. | Start with rules and a ready-made AI check; add your own scoring later. |
| Privacy | Screening processes personal data. | Collect only what you need and explain it in your privacy policy (see privacy law compliance). |
3. Preventing fake profiles in marketplaces
Fake profiles are where most scams and spam start, so make them expensive to create and easy to spot.
- Email confirmation: users confirm they own the address before they can post, and disposable email domains are blocked.
- Bot checks at sign-up: a captcha on registration, login and posting stops accounts created in bulk.
- Seller verification: ask the sellers who carry the most risk (high-value categories, businesses, high-volume sellers) for an ID or business document, and show a badge once it is checked. Verifying only this group adds little friction for casual users. Delete the document once you have decided, unless you must keep it.
- Two-step login: a code from an authenticator app or SMS stops most account takeovers, even when a password has leaked.
- Reviews and history: ratings, "member since" dates and response times help buyers judge a seller. See reviews, ratings and verified sellers.
4. Keep messages and payments on your site
Most large losses happen after a conversation moves to another app and the payment moves to a method that can't be reversed. On-site messaging lets you warn users at the right moment, for example when a message asks for a gift card, a wire transfer or a one-time code. The FTC's advice to buyers and sellers is a good basis for your safety tips:
| Payment method | Risk |
|---|---|
| Credit card | The safest option for buyers: card payments come with legal protections, and buyers can dispute a charge (FTC). |
| Your site's own checkout | Keeps whatever protection the site offers. The FTC tells buyers not to buy from anyone who wants them to pay outside the marketplace's payment system. |
| Wire transfer, gift cards, reload cards, crypto | "Like sending cash": once the money is gone, it generally can't be recovered (FTC). |
| Check | A fake check can look cleared for days before the bank takes the money back. Sellers should never deposit a check for more than the selling price (FTC). |
| Payment apps with strangers | Watch for fake payment notifications and bogus refund requests; check the payment in your own account before handing anything over (FTC). |
5. Make reporting easy and act on every report
Your users see scams before you do. Put a "report this listing" button on every listing, collect reports in one queue, and answer them. A simple workflow:
- Automated filters and user reports flag a listing or account.
- A moderator reviews it and decides to keep, edit, hide or remove it, or to block the account.
- The seller gets a short statement of the reason and a way to appeal.
- Complex or high-value cases go to a senior moderator or the owner.
Telling users why you acted is a legal duty in the EU (see below), and it cuts repeat support tickets. For rules, roles and queues, see moderation and marketplace policies.
6. Teach buyers and sellers what to watch for
- Show short safety tips on every listing page: meet in a public place, see the item before paying, never pay a deposit by bank transfer, gift card or crypto, never share a one-time code.
- Warn that offers far below market price are a red flag, and that buyers should ask for more photos and details.
- Explain how to report a listing on your site, and point US users to ReportFraud.ftc.gov and IC3.gov if they lose money.
- Write your terms so they say what counts as fraud and what happens to accounts that commit it, and apply them consistently.
7. Have a plan for when fraud gets through
- Contain: hide the listings and suspend the account straight away.
- Investigate: look for other accounts, listings or messages linked to the same person.
- Tell the people affected: warn buyers who were in contact with the account and explain what you did.
- Fix the gap: add the pattern to your filters or rules and document what happened.
When the problem is a disagreement between a buyer and a seller rather than fraud, follow a clear dispute process, and make sure your support team knows when to escalate.
Marketplace spam prevention
Spam and fraud overlap: many scam listings arrive as spam, from accounts created in bulk. On a classifieds site spam usually means:
- Bot posts: automated accounts posting irrelevant or malicious listings.
- Duplicate listings: the same ad posted many times to flood a category.
- Keyword stuffing: listings packed with search terms to rank higher.
- Mass messaging: the same unsolicited message sent to many users, often with a phishing link.
- Inappropriate content: listings that break your rules or the law.
How to stop spam
- Captcha on sign-up, login and posting. It stops most bots with little effort.
- Limits: cap listings per day, contact messages and login attempts per user, so one account can't flood your site.
- Block disposable email domains and known spam emails and domains.
- Banned words: block or mask words and phrases you never want to see.
- Spam filters such as Akismet check text against known spam.
- IP blocking with care: blocking addresses or whole countries can stop persistent spammers, but can also lock out genuine users, for example people on shared or mobile networks.
| Captcha | Cost (as of October 2026) |
|---|---|
| Google reCAPTCHA | Free up to 10,000 assessments a month; a billing method in Google Cloud is required even for the free tier. Premium: $8 flat for 10,001 to 100,000 a month (Google Cloud). |
| Cloudflare Turnstile | Free plan with unlimited challenges and up to 20 widgets. It usually shows no puzzle and can be used without other Cloudflare services (Cloudflare). |
A practical starting setup for a small site: a free captcha and email confirmation on sign-up, approval of new accounts' first listings, blocked disposable email domains, daily posting limits and a "report this listing" button. Pay for machine-learning fraud tools only once your own reports show patterns that rules no longer catch. Every extra step costs some genuine users, so test changes and watch your sign-up numbers.
What the law expects from marketplaces
Some fraud and spam controls are now legal duties. This is a summary, not legal advice: check with a lawyer how these rules apply to your site.
| Rule | Who it covers | What you must do |
|---|---|---|
| US INFORM Consumers Act (in force since 27 June 2023) | Online marketplaces with "high-volume" third-party sellers: 200 or more separate sales of new or unused consumer products and $5,000 or more in gross revenue in any continuous 12-month period during the past 24 months. Only sales where the marketplace processed the payment count. | Collect the seller's bank account, tax ID and contact details and verify them within 10 days. Have sellers certify their details at least once a year, and suspend those who don't. For sellers with $20,000 or more a year on your site, show their name, physical address and contact details to buyers. Give buyers a clear way to report suspicious conduct on those sellers' listings. The maximum civil penalty is $53,088 per violation (current 16 CFR 1.98 figure, set in January 2025). |
| EU Digital Services Act (applies to all regulated services since 17 February 2024) | Hosting services and online platforms with users in the EU. Micro and small enterprises (fewer than 50 staff and an annual turnover or balance sheet of no more than €10 million) are exempt from the extra duties for online platforms and marketplaces, unless designated as very large online platforms, but the basic hosting duties still apply. | Let users flag illegal content and goods; process reports in good time and tell both sides what you decided; give a statement of reasons when you remove or restrict content or suspend an account. Platforms must also offer an internal complaints system. Marketplaces must collect and check traders' identity, contact, payment and trade-register details before they sell to EU consumers, and suspend traders whose details are wrong (Article 30; exemption in Article 29). |
A classifieds site where private people sell used goods may have few or no sellers who reach the INFORM thresholds, and the DSA's trader rules only cover business sellers. If dealers, shops or agencies sell on your site, check whether they do. Data you collect for verification is personal data under the GDPR and US state privacy laws; see data privacy and security.
Security without scaring off genuine users
- Add friction where the risk is. Verify high-value categories and business sellers, not every visitor; ask new accounts for more than trusted ones.
- Combine automation with people. Filters handle volume; moderators handle the doubtful cases and keep false positives down.
- Warn without alarming. Short, specific tips at the right moment work better than long warnings nobody reads.
- Review regularly. Scammers change tactics, so look at your reports every few weeks and update your rules.
Doing this with Yclas
If you run your marketplace on Yclas, the controls above are built in:
- Publishing: choose whether listings go live straight away, after approval, after the seller confirms their email, or after payment.
- AI check (Starter, Professional and Marketplace plans): every new listing is screened for scam patterns and for your own rules written in plain language. Risky listings wait in a moderation queue with the reason; nothing is deleted.
- Message warnings: buyers and sellers are warned when a message asks for gift cards, wire transfers or one-time codes.
- Reports: a Report button on every listing with DSA reasons, a reports queue, and a statement of reasons emailed to the seller when you act.
- Seller verification and reviews: sellers upload an ID or business document, your team approves or rejects it, and the document is deleted once decided. Badges show Verified, ID verified and Verified business, plus earned badges (Top rated, Fast responder, Member since). Business accounts can be approved with their trader details for the DSA.
- Spam protection: Cloudflare Turnstile, Google reCAPTCHA or a built-in captcha; disposable email blocking; banned words blocked or masked; Akismet; blocked emails and domains; a black list; limits on listings per day, contact messages and login attempts.
- Escrow.com payments: for high-value items, you can let buyers pay through Escrow.com. Sellers connect their own Escrow.com account, and Escrow.com holds the payment until the buyer accepts the item.
- Accounts and team: two-step login with an authenticator app or SMS, moderator roles, an audit log nobody can edit or delete, and safety tips on listing pages.
You can try it with a free 15-day trial; see pricing for the plans.
Frequently asked questions
What are the most common scams on classifieds sites and marketplaces?
Fake listings (especially rentals, pets, tickets and vehicles), requests for deposits or fees before a viewing, overpayment with fake checks, fake payment notifications, phishing links, requests for one-time codes, pressure to pay off the platform, and account takeovers.
How do I prevent scams on my classifieds site?
Hold new accounts' first listings and high-risk categories for approval, screen listings for scam patterns, keep messages on your site with warnings about gift cards, wire transfers and codes, verify high-risk sellers, add a report button to every listing and act on reports.
How do I prevent fake profiles in a marketplace?
Require email confirmation, block disposable email domains, put a captcha on sign-up and posting, limit how much a new account can do, and verify sellers in high-risk categories with an ID or business document.
How do I stop spam on a marketplace?
Use a captcha, daily posting and messaging limits, banned words, a spam filter such as Akismet and email and domain blocklists. Approve first listings from new accounts and let users report spam.
Can AI replace human moderators?
No. AI is good at screening every listing and flagging likely scams, but it makes mistakes. Use it to hold risky listings for review, and keep a person in charge of the final decision and of appeals.
Do small marketplaces have to follow the DSA and the INFORM Act?
Partly. Under the DSA, micro and small companies are exempt from the extra platform and marketplace duties but still need a way for users to report illegal content and must give reasons when they remove it. The INFORM Act depends on whether your sellers reach its high-volume thresholds. This is not legal advice.
