Bot protection for your inbox
The CAPTCHA
for your inbox.
Stop AI spam from flooding your inbox and calendar. Known contacts get through instantly. Everyone else proves they're human first.
Closed beta · Gmail only · 5-minute setup · Archived, never deleted
Incoming email
sarah@designco.com
Re: new design direction
The problem
Inboxes are broken.
AI has made cold outreach nearly free. Real messages get buried under the noise.
Spam filters catch the obvious, but plausible outreach slips through — and calendar invites bypass filters entirely. You miss what matters and drown in what you didn't ask for.
How it works
Up and running in minutes.
Connect Gmail once
Sign in with Google. Captchainbox scans your sent history and whitelists everyone you've written to. No one you know gets blocked. Under five minutes.
Gmail connected
Analyzing sent history…
a.rivera@coldoutreach.io
Quick opportunity for you
Every email is silently checked
New email arrives. Captchainbox checks the sender instantly. Known contacts reach your inbox. Unknown senders are archived, never deleted, and sent a CAPTCHA link. Calendar invites from unknowns are auto-declined.
Real people verify in 30 seconds. Bots can't. Nothing is lost.
Real people get through in 30 seconds
Unknown senders get a simple CAPTCHA. Complete it and their message is delivered immediately — trusted for 3 days, no re-verification for follow-ups.
Inbox verification
Complete this quick check to prove you're human and get your message delivered.
Pricing
One plan. Everything included.
Free 7-day trial, no credit card required.
We never read your emails.
Filters by sender identity only — never content. Your conversations stay private.
Take back your inbox.
Join the waitlist for early access.