The filter builder your inbox should have.

Create richer rules, test them on real mail, and see why every message moved. Works with Gmail and Outlook.

Build a filter Run free audit
  • 20 conditionsper filter
  • 3 logic levelsfor nested rules
  • Preview firstbefore activation
  • Explainevery match
A precision sorting machine routing email into separate paths

Verified connections and security assessment

  • Google OAuth verified
  • Microsoft OAuth verified
  • CASA Tier 2 AL1 verified

More than a rule form.

KeepKnown gives filters a builder, a test bench, and a decision log.

Build the exact match.

Combine sender, contact, domain, subject, header, history, and mailbox signals with nested all, any, and exception logic.

  • Unknown sender
  • Saved contact
  • Replied before
  • Newsletter
  • Has attachment
Product walkthrough Illustrative demo
Manual builder Signal catalogue AI draft

Rules that know relationships.

Filter by contacts, approved domains, people you replied to, VIPs, and your own sender groups.

  • Contacts
  • Approved domains
  • Replied before
  • VIPs
  • Sender groups

More useful outcomes.

Keep, move, label, prioritize, hold for review, or add matching mail to a digest.

  • Keep
  • Move
  • Label
  • Prioritize
  • Hold for review
  • Add to digest

Filters your inbox can’t build alone.

Start with a useful rule, see exactly what it does, then make it yours.

Every day

  1. Known senders pass

    Contacts, approved domains, and prior replies stay in your inbox.

    Build this filter

  2. Critical unknowns get reviewed

    New senders with critical subjects enter Priority Review.

    Build this filter

  3. Newsletters wait for a digest

    Newsletter mail goes to Reading Later and a weekly digest.

    Build this filter

Adapts with you

  1. Rescued senders become trusted

    A previous rescue triggers a sender or domain approval suggestion.

    Build this filter

  2. Persistent unknowns stop interrupting

    Repeated unknown senders move to Outsiders automatically.

    Build this filter

  3. Fundraise mode

    Investor, diligence, legal, and payment mail gets priority.

    Build this filter
Explore all filter recipes

Native filters stop at creation.

KeepKnown helps you design, test, run, and debug the whole system.

Capability Native filters KeepKnown
Relationship-aware signalsContacts, reply history, VIPs, and sender groups
Nested conditional groupsCombine all, any, and exception logic
Filters saved pausedNothing activates before you are ready
Safe activation modesShadow, Review Only, and Enforce
Per-match explanationsSee the filter, matching facts, and resulting action
Ready-made filter templatesInstall a working filter, then tune it

Power without the leap of faith.

Every new filter starts paused. You decide when it is ready.

New filter Paused

  1. Connect

    Link Gmail, Google Workspace, Outlook, or Microsoft 365.

  2. Build

    Write the rule in plain English or compose it condition by condition.

  3. Test and activate

    Preview real matches, choose a safe mode, and turn it on when ready.

Powerful filters. Clear data boundaries.

Core filters use sender, domain, headers, encrypted subject text, local history, and your decisions. They do not read email bodies.

Signal-only matching. Email bodies and attachment content remain outside the core filter.
Google OAuthVerified Microsoft OAuthVerified Google CASATier 2 · AL1 ActionsReversible
A shielded matching chamber accepts email signals while message bodies and attachments remain outside its boundary

Filters you stop thinking about.

Set the rule once. Let KeepKnown handle the repeat decisions.

“We used to waste so much time sorting through junk mail. Now it is clean, efficient, and stress-free.”
Taylor W. Taylor W.Founder, NAPCO Pump Company
“KeepKnown works quietly in the background, saving me hours of distraction. I do not know how anyone manages without it.”
Paul N. Paul N.CEO, Intuitive

Powerful filters. Simple pricing.

Every paid plan includes the full filter builder, safe previews, and decision history.

973,000 emails filtered

See the problem first.

Run a free Gmail audit. No card and no inbox changes.

Run free audit

Founder

One inbox with the full filter builder.

$29 $19 per month
Billed annually at $228 Save $120 with yearly billing
  • 1 Gmail or Outlook inbox
  • Advanced conditions and nested logic
  • Preview, Shadow, and Review Only
  • Templates, digests, and decision log
Build a filter
Most popular

Executive Pro

Up to three inboxes for one power user or a small team.

$69 $49 per month
Billed annually at $588 Save $240 with yearly billing
  • Up to 3 Gmail or Outlook inboxes
  • Everything in Founder
  • Multi-inbox management
  • Priority support and analytics
Build a filter

Team Gate

Central filter management, rollout help, and priority escalation for 5 or more inboxes.

From $199 per month, billed annually Contact sales

7-day trial. Add a card after connecting your inbox. 30-day money-back guarantee.

Before you build.

Short answers to the questions that matter.

What makes KeepKnown stronger than native filters?

KeepKnown adds relationship-aware signals, nested logic, templates, safe activation modes, digests, review queues, and a decision log around each filter.

What is an Inbox Protocol?

An Inbox Protocol is a saved KeepKnown filter. It defines what to match, what to do, and when the rule is active.

Does KeepKnown read email bodies?

Core filters do not read email bodies. They use sender and domain information, headers, encrypted subject text, local history, and your decisions.

Can I test a filter before it moves mail?

Yes. New filters save paused. Preview recent mail, observe in Shadow, or send decisions to Review Only before supported actions are enforced.

Which inboxes are supported?

KeepKnown supports Gmail, Google Workspace, Outlook, and Microsoft 365. Exact enforcement actions depend on provider capabilities.

Latest articles

Practical guidance for building quieter, safer inboxes in Gmail and Outlook.

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Build a better filter.

Practical Gmail and Outlook guides, with the native setup explained first.

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Google, Outlook, and teams

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