The endpoint filter that adds no supplier.

Klar filters spam inside Apple Mail, on the machine itself. The extension that reads the inbox has no network permission, so classification adds nothing to the supply chain you have to account for.

Supply chain security starts at the things nobody lists.

NIS2 puts public administration entities in scope and asks for risk-management measures that cover supply chain security, including the security of the relationships with direct suppliers and service providers. A hosted mail filter falls inside that scope: its operator reads your staff's mail.

It is also the one that gets left off, because it looks like a setting rather than a service. A cloud filter receives the message in order to score it: a supplier with a dependency, a data flow and an incident surface, all of it attached to correspondence that is often the least routine thing an authority handles.

Directive (EU) 2022/2555 (NIS2), art. 21: cybersecurity risk-management measures

Nothing to add to the chain.

Klar is a Mail extension. It scores each message on the machine as it arrives, without uploading it. The part that reads the inbox ships without macOS network permission, which one codesign command shows from the installed app itself. There is no endpoint to depend on, so there is no supplier, no data flow and nothing to review annually.

The part of Klar that reads your mail is an Apple-sandboxed Mail extension shipped without the network entitlement. It is not that we promise not to send your mail anywhere. It is that macOS refuses the connection, because the permission was never requested. Classification happens on your Mac, instantly.

What that means in practice

No network access: The free App Store app and its Mail extension ship without the network entitlement. macOS refuses any connection they try to open. This is a permission the app does not hold, not a policy it promises to follow.
The model ships with the app: The classifier is a multilingual transformer inside the app bundle. Nothing is fetched when a message arrives, so it works the same on a train as it does in the office.
No account: There is nothing to sign up for and no licence server the free app calls. Unless you contact us or choose to send an Email report, we do not know who you are.
The engine is open source: The scoring engine is AGPLv3. Your IT people do not have to take our word for any of this. They can read it, build it, and watch what it does.

Questions your compliance officer will ask

Is Klar certified or approved for public-sector use?

No, and no scheme we know of certifies a Mail extension. What can be checked instead is the property that matters: the extension carries no network entitlement, and codesign prints that from the app on the machine, without trusting us. That is a stronger check than a certificate, because it is one you run yourself and it stays true only as long as the shipped build stays true. The full walkthrough, including what App Store review, notarization and TestFlight each do and do not cover, is at how to check what a Mac app is allowed to do. The architecture behind it is at local-first.

Our mail is already filtered before delivery. Where does this fit?

At the desk, after the gateway, on what the gateway let through. That is the layer where staff actually meet a targeted message, and it is usually where a second cloud filter gets bought. Klar is that layer without a supplier. If you want the same engine at the gateway rather than a third party's, Klar Pro runs it as a milter on your own mail server.

Does filtering send anything off the machine?

No. The free App Store app and its Mail extension have no network permission. If you choose Email report, Klar opens an editable draft in your own mail app; nothing leaves until you send it. Do not include confidential correspondence unless you are authorised to share it. Klar Plus, the paid companion you install yourself, separately uses the network for its licence, model and version checks. None carries your mail. The full list is on the local-first page.

Do we need a data processing agreement with you?

That is a question for your own counsel, and it depends on which part of Klar you run. Routine filtering sends us nothing. A user who sends an Email report may share selected messages, diagnostics and a removable monthly usage summary; our privacy policy explains what we then hold. Decide whether staff may use that report action with confidential correspondence.

What we are not claiming.

We are not offering legal advice, and a spam filter does not make anyone compliant. Your obligations are yours, and your bar, your regulator or your DPO is the right place to test them. What we can tell you is exactly where the software runs and what it is permitted to do, which is the part most vendors leave you to infer.

We are also not claiming perfect filtering. No filter is, and any vendor quoting you a single accuracy number is quoting a number from their corpus, not your inbox. What we will say is that being wrong about a message on your Mac and being wrong about it on someone else's server are not the same kind of wrong.

Read the whole local-first argument

Try it on the inbox you cannot risk.

macOS 14 or later, Apple Silicon. No account, no cloud classification, no setup. It filters inside Apple Mail on your Mac.