Stop AI cold emails
from cluttering your inbox
Coldblock detects and removes AI-generated cold outreach from your Gmail inbox automatically. No more wading through templated sales pitches.
How it works
Three steps to a clean inbox
Connect Gmail
Sign in with Google and grant Coldblock read & label access.
Coldblock Scans
Every incoming email is analyzed in real-time and flagged outreach is moved within seconds.
Review & Control
Flagged emails are quarantined. Review, restore, or whitelist from your dashboard.
Coldblock works alongside Gmail, not as a mail server proxy. You may briefly see a notification before the email is moved — our pipeline typically classifies and quarantines outreach within seconds of delivery.
Features
Everything you need to fight cold outreach
A multi-layered detection system that gets smarter over time, with full transparency and control.
Real-Time Monitoring
Connected via Google Pub/Sub, Coldblock monitors your inbox the moment emails arrive. No polling, no delays.
4-Stage Classification
Header fingerprinting, domain reputation, content pattern matching, and AI verification work together for accurate detection.
Daily Digest
Get a daily summary of scanned and quarantined emails. One-click actions let you rescue false positives directly from the email.
Transparent Quarantine
See exactly why each email was flagged with confidence scores and classification reasons. Nothing is hidden.
Sender Whitelist
Whitelist trusted senders and domains so their emails are never quarantined. Full control over who gets through.
Learns From Feedback
When you mark an email as not spam, Coldblock remembers. Future emails from that sender get progressively lower scores.
Instant Backfill
Scan your recent inbox on signup to see what Coldblock would have caught. Immediate value before any new emails arrive.
Under the hood
Multi-stage detection pipeline
Most emails are classified using fast, local rule-based checks alone. AI is only used as a last resort when the rules are inconclusive — over 80% of outreach is caught before AI ever runs.
Header Analysis
35%Detects outreach platform signatures from Instantly.ai, Apollo, Lemlist, and 15+ others via X-Mailer headers and DKIM signatures.
Domain Reputation
15%WHOIS-based domain age scoring. New domains and known outreach patterns are flagged. Results cached for speed.
Content Patterns
30%Regex matching for cold outreach templates in English and Swedish. Catches booking links, follow-up phrases, and sales speak.
AI Verification
20%Only runs when the first three stages are inconclusive. Most emails never reach this step. When it does run, only the sender, subject, and a short body snippet are analyzed — never attachments or full threads.
Privacy
Your emails stay yours
Coldblock is designed with privacy first. We don't read your emails — we scan metadata and patterns.
Rules first, AI last
80% of detection uses header fingerprints, domain age, and regex patterns — no AI involved. AI only runs on the small fraction that is genuinely ambiguous.
Minimal data sent to AI
When AI does run, it only sees the sender name, subject line, and a short body snippet. Never full threads, attachments, or personal data.
You stay in control
Every flagged email shows exactly why it was caught. One click to restore false positives. Turn filtering off anytime.
Take back your inbox
Connect your Gmail account and let Coldblock handle the noise. Free during early access, transparent, and getting smarter every day.