Mass outreach gets expensive fast.
At about four cents per email, sending 100,000 cold pitches costs $4,000. Every cold outreach business depends on near-zero sending cost. Real cost at scale breaks the model.
The standard play.
The standard play against cold outreach is to keep the existing spam filter and hope. Gmail or Outlook scans each incoming message for bulk-pattern signals (large send volume, blacklisted infrastructure, suspicious links, unusual vocabulary) and flags messages that score above a threshold. A polished cold pitch from a fresh domain hits none of those signals. It walks straight into the inbox. The next layer is usually an unsubscribe link, except cold senders are not on a list, so there is nothing to unsubscribe from.
Where it falls short.
- Gmail and Outlook do not flag cold email. It is technically not spam: one sender, one recipient, polished prose. The filter has nothing to grip.
- Unsubscribe lists do nothing here. Cold senders found your address from LinkedIn, a CRM enrichment tool, a leaked database, or a public directory. There is no list to leave.
- AI-generated outreach has crossed the line where content classifiers can reliably tell it from a real first email.
- Block-sender features are reactive. The cold email already arrived. You already spent attention on it.
- Manual rules (filter by domain, by keyword, by sender) break the moment the next campaign uses a new domain. The work never ends.
Rythm’s approach.
Three things change when the protection is economic instead of probabilistic.
Real first-time senders pay and reach you.
Polite, one-tap payment notice. Real people rarely hesitate at four cents. Recruiters with a real offer, prospective clients with a real project, journalists with a real question all come through.
Your existing inbox keeps working.
Rythm runs on top of Gmail or Outlook by OAuth. No new address, no MX changes, no migration. Your spam filter, Priority Inbox, focused tabs, and personal filters all keep working.
What Rythm doesn’t do here.
Rythm cannot stop a determined attacker who is willing to pay four cents to reach a single high-value target. A small number of well-funded campaigns may pay the cover charge, accept the leakage, and move on. That is fine. Those messages arrive labeled with the payment, and the four cents settles to your wallet. The point is not to make cold email impossible; it is to break the economics of bulk cold email so the only senders who get through are the ones who genuinely valued reaching you.
One plan. One price.
Keep your existing Gmail or Outlook. Cancel anytime.
$1.65
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Annual on Lightning includes one bonus month. See full pricing.
Frequently asked
Keep reading.
Email security for founders
Cold outreach, recruiter spam, investor impersonation, BEC. The whole founder cocktail.
Email security for marketing agencies
For people who run cold outreach professionally and now have to receive it.
How to stop cold emails
A practical guide to the difference between blocking and gating, and which one actually works.
Spam vs cold outreach
Why your filter calls one "spam" and the other "first contact," and why the labels are wrong.
The anatomy of modern cold outreach
A breakdown of how a 2026 cold email is engineered to defeat the filter you have.
