How to sell something online without wrecking your inbox
The pattern is familiar enough that people describe it in almost the same words every time. You post an ad on Monday. By Thursday the inbox that you've used for fifteen years is receiving offers for SEO services, car warranty extensions, and cheque-cashing opportunities in a country you've never visited.
It isn't a coincidence and it isn't bad luck. Posting a public ad with a contact address in it is one of the most reliable ways to end up on marketing lists, and the mechanism is simple enough to defend against once you know it.
Where the spam actually comes from
Harvesting. Automated scrapers read classified pages, forum posts and marketplace listings continuously, looking specifically for the @ character. An address in plain text on a public page is usually collected within hours of the ad going live. This is the big one, and it's the one you can actually prevent.
Data brokers and breaches. Your address may already be circulating from a breach years ago. That's not caused by your ad — but your ad adds a piece of information to it: what you own, and roughly where you live. The two get joined together.
Platform-side marketing. Create an account to post and you've usually agreed to email from the platform and, in some cases, its partners. Read the defaults on the signup form; "keep me updated" boxes are frequently pre-ticked.
Reply-based phishing. Not spam in the traditional sense, but it arrives the same way. Fake buyers send convincing messages designed to get you to a fake payment page. The counterfeit payment confirmation is the most common version of this in classifieds. The risk is highest in the categories scammers target most — see our guides to sell a car privately and used electronics classifieds.
Seven things to do before you post
1. Never put your email address in the ad text. This is the single highest-impact rule. Platform messaging and relays exist precisely so you don't have to. Check the body of your ad and any attachments before you publish — including photos, which can contain an address in the frame.
2. Use a relay rather than a throwaway address. A relay lets buyers write to you while your real address stays off the page, and replies land in the inbox you already read. A throwaway address also works, but it only helps if you actually check it, and most people stop after a week. Our Trust & Safety page explains how the relay works.
3. Skip the phone number unless you need it. A mobile number in a public ad generates calls for years, and it's harder to change than an email. If the category genuinely needs one, consider whether messages will do until you've decided the person is real.
4. Keep your footprint small for a one-off sale. An account can mean a profile, a marketing permission and a record connecting you to the listing. If you're selling one thing, prefer a site that keeps that footprint minimal — no public profile, no marketing opt-ins — and check the signup defaults before you tick anything. Some platforms even let you browse and reply without an account. See classifieds without an account.
5. Write the ad so it doesn't identify you. No photos of your house number, your car's plate, your street sign or your front door. Shoot the item against a plain background. It also makes the listing look better, which is a free bonus.
6. Set a closing date and actually close it. Most spam spirals come from ads that stay live months after the item is gone. As soon as it's sold, take the listing down — and with a relay, that also stops the messages.
7. Use a filter before you need one. Before posting, create a rule in your email that flags messages containing the item name, or set up a folder the replies go into. When the noise starts, you can deal with it in one place instead of hunting through everything.
Already posted? Damage control
If the messages have started, work through this in order:
- Edit or delete the ad now. Remove any address, phone number or identifying detail still on the page. Deleting is better than editing if the item is sold.
- Search for your own address. Put it into a search engine in quotes. You'll often find it on pages you didn't expect, and most will remove it if you ask.
- Check whether the address was in an old breach. A breach-check service will tell you if your address is already circulating, which explains spam that predates the ad.
- Filter, don't just delete. Deleting one message doesn't stop the next. A rule that sends anything containing the item name out of your main inbox makes the volume manageable immediately.
- Change the address if it's severe. For a genuinely flooded inbox, moving to a new address for personal mail is annoying but effective. If you do, use a relay for the next listing.
- Report the phishing separately. Fake payment confirmations and "buyer" messages linking to odd pages aren't spam — forward them to the platform and delete them.
Why a relay beats a throwaway address
Both keep your real address off the page. The difference is where the replies go.
A throwaway address means a second inbox, a second password, and a second place to forget to look. In practice people check it for three days and then stop — which is roughly when the one serious buyer writes.
A relay forwards everything to the inbox you already read every day. There's nothing new to manage, and nothing to forget. When the item sells you close the ad, the relay goes quiet, and your main address was never on the page in the first place.
The replies that aren't from buyers
Every listing attracts a few messages that aren't from buyers. The common ones are someone offering to "promote" your ad, a buyer happy to pay by cheque for more than the asking price, and a link to a payment page that looks almost — but not quite — right.
None of them need a reply. Delete them, and if the platform has a report button, use it; reports are how patterns get spotted. What you shouldn't do is argue with them or click anything they send. A genuine buyer asks about the item: condition, dimensions, when they can come and see it. That difference is usually obvious once you know to look for it.
Want the full mechanism? See post a classified ad without sharing your email, explained step by step.
FAQ
Why did I start getting spam after posting a classified ad?
Because an email address on a public page gets collected by automated scrapers, often within hours. Once harvested, it's added to marketing lists that are sold and reused. The ad is the trigger, not the cause of spam in general.
Does hiding my email stop spam completely?
It stops the most common route — scraping. It won't undo a previous breach, and it won't stop someone replying to the ad with a phishing attempt. Treat it as removing the biggest source, not as a shield.
Is a throwaway email address enough?
It works, but reliability is the weak point. Replies go to an inbox you don't check often, so genuine enquiries get missed. A relay forwards to your normal inbox and keeps your address off the page at the same time.
Do marketplaces like Facebook or eBay cause this too?
Less often, because they route messages through the platform rather than publishing your address. The risk there is different: marketing email from the platform itself, and your profile being visible to buyers.
What should I do if a "buyer" sends a payment screenshot?
Treat it as a scam until proven otherwise. Check your own bank or payment app directly — never through a link in their message — and don't hand over the item until the money is actually there. No platform on either side verifies this for you; MingList certainly doesn't, since we never handle payments.
No account to browse or reply. Your email is never shown. Every reply reaches you through MingList's anonymous email relay. Free to post, free to browse.