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
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.
- 20 conditionsper filter
- 3 logic levelsfor nested rules
- Preview firstbefore activation
- Explainevery match
Verified connections and security assessment
More than a rule form.
KeepKnown gives filters a builder, a test bench, and a decision log.
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
-
Known senders pass
Contacts, approved domains, and prior replies stay in your inbox.
Build this filter -
Critical unknowns get reviewed
New senders with critical subjects enter Priority Review.
Build this filter -
Newsletters wait for a digest
Newsletter mail goes to Reading Later and a weekly digest.
Build this filter
Adapts with you
-
Rescued senders become trusted
A previous rescue triggers a sender or domain approval suggestion.
Build this filter -
Persistent unknowns stop interrupting
Repeated unknown senders move to Outsiders automatically.
Build this filter
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
-
Connect
Link Gmail, Google Workspace, Outlook, or Microsoft 365.
-
Build
Write the rule in plain English or compose it condition by condition.
-
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
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.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.CEO, Intuitive
Powerful filters. Simple pricing.
Every paid plan includes the full filter builder, safe previews, and decision history.
961,049 emails filteredSee the problem first.
Run a free Gmail audit. No card and no inbox changes.
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
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
Team Gate
Central filter management, rollout help, and priority escalation for 5 or more inboxes.
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.
Email Sender Authentication: How SPF, DKIM, and DMARC Work
Learn how email sender authentication works with SPF, DKIM, and DMARC. A practical guide to setup, enforcement, and protecting your domain from spoofing.
Read article
Domain Lists for Gmail and Outlook: A Practical Setup Guide
Learn how to build, sync, and maintain domain lists across Gmail, Outlook, and Microsoft 365. Covers wildcards, governance, and safe routing.
Read article
Gmail Safe List: How Allow-Listing Actually Works
Learn how a Gmail safe list works for personal and Workspace accounts. Compare native controls, admin policies, and advanced filter options for trusted senders.
Read article
Build a better filter.
Practical Gmail and Outlook guides, with the native setup explained first.
Gmail filtering
- Gmail Filters Learn how Gmail filters work, which criteria and actions are available, how to test rules safely, and where KeepKnown adds richer filtering.
- Gmail Filter Sender Not in Contacts Gmail has no sender not in contacts filter. KeepKnown checks Google Contacts, moves unknown senders to KK:OUTSIDERS, and deletes nothing.
- Gmail Only Allow Emails From Contacts Gmail cannot natively allow only emails from contacts. Use KeepKnown to screen non-contact senders into KK:OUTSIDERS while keeping every email recoverable.
Gmail search cleanup
- Gmail Search Operators A practical Gmail search reference for from:, subject:, in:anywhere, is:unread, older:, newer:, has:attachment, and exact phrase search.
- Gmail Search Operator in:anywhere Use in:anywhere to search Gmail beyond the inbox, including archived mail, Spam, and Trash. Includes examples with from:, subject:, newer:, and unread.
- Gmail in:anywhere and is:unread Search Operators Search in:anywhere is:unread to find unread Gmail outside the visible inbox, including archived mail, labels, Spam, and Trash.
Google, Outlook, and teams
- Review Third-Party Apps With Google Account Access Review third-party apps with access to your Google Account, understand why Substack appears there, and audit Gmail access safely.
- Outlook Whitelist-Only Mode Compare safe senders, contacts, inbox rules, and KeepKnown's recoverable routing for an Outlook or Microsoft 365 whitelist-only workflow.
- EmailGuru Is Now KeepKnown EmailGuru is now KeepKnown. Run a free inbox audit or connect Gmail and Outlook to screen unknown senders while keeping every email recoverable.
- Run a free Gmail audit Count unknown senders before changing a rule.