Bad addresses pile up from typos, natural decay, and the bot and spam signups flooding your forms — and each one bills you three separate times before it ever fails to open.
Every signup costs you — ad spend, a lead magnet, a giveaway entry. A typo or a bot signup burns that the second it lands on your list.
Mailchimp, Klaviyo and the rest charge by contact or by send. Every dead and fake address is a line item on your invoice — month after month.
Bounces and spam-trap hits drag inbox placement down for your entire list — so even your real subscribers start landing in spam.
We think it’s just plain wrong that one bad address should bill you three times.
We got tired of cleaning lists by hand, too — exporting CSVs, hunting typos, re-importing, every single month. So we built the tool we wanted: one that just quietly does it for you.
Connect once. mailfloss does the rest in the background — forever.
Most verification services see [email protected], mark it invalid, and trash it. mailfloss recognizes the pattern, fixes the domain, and keeps the subscriber on your list — across every other autopilot product.
After you connect your email platform, Instafloss verifies every new signup the moment it lands — stopping the bot and spam signups, fakes, disposables, role accounts, and dead domains before they ever pollute your list. (For verification on opt-in forms, see our JS form widget.)
Can’t add a JavaScript snippet? Autofloss runs once a day, scanning every new subscriber from the last 24 hours and removing anything that didn’t survive validation.
Subscribers go stale. Inboxes get abandoned, jobs change, domains expire. decay protection sweeps your entire list periodically and quietly removes addresses that have rotted since they joined.
mailfloss is most powerful when connected to your email platform, but it works just as well as a standalone verifier, a developer API, or anywhere in between.
One-click connect into Mailchimp, Klaviyo, HubSpot, ActiveCampaign, and 35+ others. Daily auto-cleanup, real-time signup blocker, decay protection — all on autopilot.
Drag and drop a list of any size. mailfloss returns a clean file in minutes. Pay per credit — no subscription required.
Paste 1 or 100,000 addresses directly into the mailfloss dashboard. Results stream back as we work.
Verify emails right inside Google Sheets with our extension. Cells get a green check, red x, or fixed-typo result — in place.
Same idea, inside Airtable. Add a verification field to any table and watch the rows clean themselves.
Verify any email in any workflow. Filter out bad addresses before they hit your CRM, your support tool, or your billing system.
Drop a JavaScript snippet on any opt-in form. Blocks typos, fakes, and disposables before the form submits. Separate from Instafloss — use it when you can’t (or don’t want to) route signups through your email platform first.
Get notified when mailfloss verifies, fixes, or removes an address. Wire it into anything — Slack, your data warehouse, your CRM.
Programmatic single-email verification + bulk endpoints. The same engine that powers everything else, exposed as REST. Built for AI agents and product integrations.
5,000+ teams clean their lists with mailfloss every day. Here’s what some of them say.
mailfloss was easy to set up and integrate with my email service provider. Just a few clicks and then I could let it run in the background and not worry about maintenance or daily adjustments.
I was able to quickly and easily install mailfloss. It allowed us to weed out lots of bad emails and protect our sender score. It’s one of the best martech purchases you’ll ever make. Highly recommend it.
This used to be a very tedious and time consuming process that I did manually. With no troubleshooting and very easy configuration, I have literally saved myself hours of work every single week.
We enjoy having amazing clean email data every day and a fantastic sender reputation. No blacklists, all time low email bounce rate. We have tried other email verifiers. But nothing comes close to mailfloss.
We were looking for an email validation service that could support enterprise level volume and tight integration with HubSpot, and frankly mailfloss was the only game in town.
Amazing software. I needed to clean up all of my database contacts and didn’t know the best way to do it. With mailfloss and the Brevo integration I did a big fix.
mailfloss is an email verification service built for marketers. It connects to your email platform — Mailchimp, Klaviyo, HubSpot, ActiveCampaign, and 35+ others — and quietly removes the bad addresses dragging down your sender reputation.
Where most verification tools force you to export your list, run a check, and re-import the results, mailfloss runs continuously in the background. Typos like [email protected] get fixed in place. Disposable, role, and dead-inbox addresses get removed. New signups get validated in real-time. Older subscribers get re-checked on a schedule.
For email marketers running campaigns from a supported platform, it’s a set-it-once tool. For one-off bulk lists, prepaid credits handle CSV uploads without any platform integration. For developers, a REST API exposes the same engine.
