Make unknown senders work to get into your inbox.
Stop AI spam from flooding your inbox and calendar. Unknown senders solve a CAPTCHA or pay a fee to get in. Trusted contacts get through as usual.
7-day free trial · 5-minute setup · Archived, never deleted
Prove you are human
Sarah Chen
sarah@designco.com
Re: new design direction
SCSarah ChenRe: new design directionnow
Sarah Chen
Re: new design direction
SStripeReceipt for your subscription6m
Stripe
Receipt for your subscription
LLinearPR #842 was merged1h
Linear
PR #842 was merged
Proceedings are donated to
Pooled and donated annually, 50/50. See the ledger.
Built for inboxes overwhelmed by AI outreach
AI cold outreach is nearly free. Make senders work for your time and attention.
Spam filters catch the obvious, but mass-customized outreach gets through. You miss what matters and drown in what you didn't ask for.
Step 01
Sign in with your email provider.
Captchainbox scans your conversation metadata. We never read your messages. We build a trusted sender and domains list for you.
Sign in with your email provider
Gmail connected
you@gmail.com
Analyzed
2,847
Trusted
284
Status
Active
Step 02
Every sender checked silently.
For every new email Captchainbox checks the sender against your trusted contacts. Unknown senders are archived (never deleted) and sent a verification link. Introductions through trusted contacts get through.
Step 03
Senders show they are worth your time and attention.
Unknown senders verify through a CAPTCHA or pay a small fee to show they are relevant to you. They complete the verification and their email is delivered to your inbox. Payment fees get pooled and donated.
See the verification flow in action
Inbox verification
This inbox uses a quick CAPTCHA. Complete it to get your message delivered.
Complete the CAPTCHA
You're verified
Your message is on its way to their inbox.
Pricing
Simple pricing to get back your time and attention.
Free 7-day trial, no credit card required.
Pay once, keep forever
7-day free trial included
Real-time inbox filtering
Calendar invite protection
Trusted circle from sent history
Introduction detection via CC
Configurable filter rules
Custom auto-reply templates
Emails archived, never deleted
Take back your inbox.
Set up in 5 minutes. Free to get started.
Curious what senders see? Send me an email and see the verification flow yourself.