# KeepKnown

> KeepKnown is an email screener for Gmail and Outlook: only people you know reach the inbox. Senders who are not in your contacts, approved (VIP) domains, or past conversations move to a KK:OUTSIDERS label (Gmail) or category (Outlook) for review. Nothing is deleted or bounced. In Gmail, KeepKnown replies once from the user's address to each real person it screens out, with a link to say in one line why the message matters; the reply is on by default and the user can switch it off in settings. Mailing lists, automated senders and unverified mail never get a reply.

KeepKnown works with Gmail, Google Workspace, Outlook.com, and Microsoft 365 accounts connected through Google or Microsoft authorization. Contact screening uses sender metadata and your contacts, not message bodies. Contact lookups use per-user keyed hashes (HMAC-SHA256) instead of plain-text address lists. Users can also write inbox rules in plain English, preview the matching mail, and activate a rule when it looks right; each routing decision is logged.

Neither Gmail nor Outlook has a native "only allow email from my contacts" switch. Gmail filters cannot test whether a sender is a contact, and Outlook's closest option (trusting only Safe senders) sends everyone else to Junk alongside spam. KeepKnown fills that gap. It is not a spam filter: it decides by who the sender is, which also catches polite cold outreach that spam filters let through.

Pricing (USD):
- Founder: $12.99/month or $99.99/year (1 protected inbox)
- Executive Pro: $29.99/month or $229.99/year (Up to 3 protected inboxes)
- Free: Gmail inbox audit that counts unknown senders without changing the inbox

## Product

- [KeepKnown home](https://keepknown.com/): Product overview and plain-English rule builder
- [Pricing](https://keepknown.com/pricing/): Plans, billing options, and what each plan includes
- [Free Gmail audit](https://keepknown.com/ghost-audit/): Count senders outside your contacts using metadata only; no inbox changes
- [Chrome extension](https://keepknown.com/extension/): Gmail extension with a local stranger audit
- [Team Gate](https://keepknown.com/agency-contact/): Contact form for teams and agencies

## Keep strangers and cold email out

- [Gmail Only Allow Emails From Contacts](https://keepknown.com/gmail-only-allow-emails-from-contacts/): Gmail has no contacts-only setting. Three ways to get one: an allow-list filter, a free Apps Script, or KeepKnown. Steps, a copy-paste script, and limits.
- [Block Unknown Senders in Gmail](https://keepknown.com/block-unknown-senders-gmail/): Gmail can't block every unknown sender at once. Compare Block sender, an allow-list filter, Workspace rules and contact screening, with steps and limits.
- [Email Screener for Gmail and Outlook](https://keepknown.com/email-screener/): An email screener holds mail from new senders until you decide. How it works in Gmail and Outlook, with KeepKnown, Clean Email, SaneBox, HEY and Spark compared.
- [HEY Screener for Gmail](https://keepknown.com/hey-screener-for-gmail/): HEY's Screener needs a HEY address. To screen first-time senders and keep Gmail, forward to HEY, use Spark's Gatekeeper, or add KeepKnown. Prices compared.
- [Block Cold Emails in Gmail](https://keepknown.com/block-cold-emails-gmail/): Cold outreach passes Gmail's spam checks because it comes from real, authenticated senders. What works: block, filter, alias, and contact screening.
- [SaneBox Alternatives](https://keepknown.com/sanebox-alternatives/): Compare SaneBox with KeepKnown, Clean Email, Spark, HEY, and Gmail filters: how each sorts or screens mail, where it works, what it costs, and who it suits.
- [KeepKnown vs SaneBox](https://keepknown.com/keepknown-vs-sanebox/): KeepKnown keeps known senders in the inbox and moves strangers aside; SaneBox learns from how you file mail. Features, providers, and prices compared.
- [Clean Email Alternatives](https://keepknown.com/clean-email-alternative/): Clean Email cleans up a backlog and can screen new senders. Compare it with KeepKnown, SaneBox, Spark, HEY, and Gmail's own tools on approach and price.
- [How to Block Emails on Gmail](https://keepknown.com/how-to-block-emails-gmail/): Open the email, tap More (the three dots) next to Reply, then Block. Steps for the Gmail app and the web, plus domains, many senders and unblocking.
- [Email Bombing](https://keepknown.com/email-bombing/): Inbox flooded with sign-up emails? Here is what email bombing is, the first three things to do, and how to stop the flood in Gmail and Outlook.
- [How to Stop Spam Emails](https://keepknown.com/stop-spam-emails/): Report spam, filter repeat senders, stop replying, use a sign-up alias. Steps for Gmail, Outlook and iPhone, plus why you suddenly get so much spam.
- [Gmail Whitelist](https://keepknown.com/gmail-whitelist/): Gmail has no whitelist button. Add the sender to Contacts or make a filter with Never send it to Spam. Steps for Gmail, Outlook, Yahoo and Apple Mail.
- [How to Block Emails on Outlook](https://keepknown.com/how-to-block-emails-outlook/): Block a sender or a whole domain in Outlook.com, new Outlook, classic Outlook and the app. Plus unblocking, the 10,000 limit and why blocks fail.
- [Outlook Rules](https://keepknown.com/outlook-rules/): Create rules in Outlook.com, new Outlook, classic Outlook and Mac. Recipes that keep unwanted mail out, why rules stop working, and what they can't do.
- [Stop Recruiter Emails in Gmail](https://keepknown.com/stop-recruiter-emails-gmail/): Block, filter or screen recruiter cold emails in Gmail and Outlook. What native tools handle, where they fail, and how to review recruiters on your schedule.
- [Stop PR Pitches in Your Inbox](https://keepknown.com/stop-pr-pitches-email/): Too many press pitches? Block, filter or screen PR emails in Gmail and Outlook without losing real tips. Native options, limits, and sender-based screening.
- [Stop Cold Emails as a Founder or Executive](https://keepknown.com/stop-cold-emails-founders-executives/): Founder and executive inboxes attract sales outreach, investor and vendor pitches. Native Gmail and Outlook options, their limits, and sender screening.
- [Gmail Filter Sender Not in Contacts](https://keepknown.com/gmail-filter-unknown-senders/): Gmail filters can't check your contacts. Use -from: exclusions, a free Apps Script, or KeepKnown to label senders not in contacts. Steps and comparison.
- [Outlook Whitelist-Only Mode](https://keepknown.com/outlook-whitelist-only-mode/): Block all Outlook email except contacts: Sender Screening, Safe Lists Only, a contacts rule, admin mail flow rules, and a recoverable option. Steps and limits.

## Trust and privacy

- [How KeepKnown Handles Your Email](https://keepknown.com/how-keepknown-handles-your-email/): KeepKnown screens senders using headers and your contacts, not message bodies. What it reads, stores, encrypts and sends to AI or third parties, stated plainly.


## Gmail filtering

- [How to Create Email Filters](https://keepknown.com/how-to-create-email-filters/): Step-by-step email filters for Gmail, Outlook, Apple Mail and Yahoo, plus a free filter creator that writes the Gmail search, import file and Outlook rule.
- [Gmail Filters](https://keepknown.com/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 Action Categorize As](https://keepknown.com/gmail-filter-categorize-as-social-promotions-updates/): Use Gmail filter action Categorize as to route messages to Primary, Social, Promotions, Updates, or Forums, and know when category filters stop helping.
- [Apply Gmail Filters to Existing Emails](https://keepknown.com/apply-gmail-filters-to-existing-emails/): Tick Also apply filter to matching conversations when you create or edit a Gmail filter and it runs on old emails too. Steps for new and existing filters.
- [Gmail Filter Multiple Keywords](https://keepknown.com/gmail-filter-multiple-keywords/): Create Gmail filters with multiple keywords using OR, quoted exact phrases, braces, sender groups, and subject terms, then know when keyword filters are not enough.
- [Gmail Filter Mark as Important](https://keepknown.com/gmail-filter-mark-as-important/): Use a Gmail filter to mark matching mail as important, search is:important is:unread, and know why important markers do not stop unknown senders.
- [Gmail Auto Label Emails](https://keepknown.com/gmail-auto-label-emails/): Automatically label Gmail messages by sender, subject, keyword, category, or attachment, with examples for receipts, newsletters, and unknown senders.

## Gmail search cleanup

- [Gmail Search Operators](https://keepknown.com/gmail-search-operators/): Every Gmail search operator in one table: from:, to:, subject:, is:unread, in:anywhere, has:attachment, older_than:, newer_than: and more, with examples.
- [Gmail Search Operator in:anywhere](https://keepknown.com/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 is:unread Search](https://keepknown.com/gmail-search-in-anywhere-is-unread/): Type is:unread in Gmail search to show only unread emails. Add category:primary or in:anywhere to find unread mail in Primary, archive, Spam, or Trash.
- [Gmail label:unread vs is:unread](https://keepknown.com/gmail-label-unread-vs-is-unread/): See when label:unread and is:unread return the same mail, where they differ, and which query to use for inbox, labels, and archived messages.
- [Gmail Advanced Search Fields](https://keepknown.com/gmail-advanced-search-fields/): Map Gmail advanced search fields to operators for sender, recipient, subject, date, unread, attachments, labels, and categories, then automate recurring inbox rules.
- [Find Important Unanswered Emails](https://keepknown.com/find-important-unanswered-emails/): Use Gmail and Outlook searches to find important unanswered emails, then reduce new misses by screening unknown senders before they hit the inbox.

## Google, Outlook, and teams

- [Review Third-Party Apps With Google Account Access](https://keepknown.com/google-third-party-apps-access-audit/): Review third-party apps with access to your Google Account, understand why Substack appears there, and audit Gmail access safely.
- [EmailGuru Is Now KeepKnown](https://keepknown.com/emailguru/): EmailGuru is now KeepKnown. Run a free inbox audit or connect Gmail and Outlook to screen unknown senders while keeping every email recoverable.

## Optional

- [Articles](https://keepknown.com/articles/): Guides on email privacy, security, filtering, and deliverability
- [Privacy policy](https://keepknown.com/privacy-policy/): How KeepKnown handles account and email data
- [Terms of service](https://keepknown.com/terms-services/)
- Contact: hello@keepknown.com