Choosing a spam filter

The honest picks

SpamSieve

A proven on-device filter with two decades of history. Pick it if you like Bayesian filtering you train yourself and want a mature indie tool. Klar takes a different bet on the model: a multilingual transformer instead of word statistics.

SaneBox

Not primarily a spam filter: it sorts your inbox by importance, in the cloud. Pick it if your problem is too much legitimate mail and you are comfortable giving a service access to your mailbox.

Gmail

Very good and included. If you live in Gmail's own apps and are fine with Google processing your mail, you may not need anything else. Klar earns its place when your accounts land in Apple Mail.

Microsoft 365

Exchange Online Protection is on for every Microsoft 365 mailbox and your admin manages it. On a work account, that decision is usually made for you. Klar still helps with what reaches Apple Mail.

Libraesva

An EU email security gateway for organizations that run their own mail: appliance, sandboxing, compliance tooling. It is not aimed at individuals.For a lightweight self-hosted layer, see Klar Pro.

SpamAssassin

The classic open-source filter: rules plus Bayesian scoring, two decades of deployment. Powerful once tuned, but it lives on a mail server you run and maintain, not on your Mac.For a lightweight self-hosted layer, see Klar Pro.

Rspamd

A fast, modern open-source filter for self-hosted mail: rich signals and scriptable rules, built for server operators. It filters at the server, not in your Mac's inbox.For a lightweight self-hosted layer, see Klar Pro.

Mailinblack

A French email security service for organizations. It filters mail at the gateway, runs fake phishing attacks to train staff, and gives admins a console. Aimed at companies, not individuals reading mail in Apple Mail.

Leave Me Alone

Built for bulk unsubscribing: it follows unsubscribe links for you and rolls newsletters into digests. Its spam blocker learns in its cloud and targets cold outreach. Pick it to prune subscriptions, not as a spam filter.

Clean Email

The pick for digging out an overflowing mailbox: smart folders act on thousands of messages at once, rules keep it tidy, and it reads headers only. Filtering means rules you define yourself, so pick it for cleanup, not detection.

Inbox Zero

Not a spam filter: it is an assistant that sorts your inbox, drafts replies in your style, blocks cold outreach and unsubscribes in bulk. It is SOC 2 Type 2 certified, its source is public, and a self-hosted install can run against a local model. Pick it if you want that assistant across Gmail or Outlook and are comfortable with the access it needs.

MailWasher

A veteran Windows tool with a distinct approach: inspect mail on the server and delete junk before it reaches your machine, with Bayesian learning and blocklists. On a Windows PC with POP or IMAP it earns its keep. There is no Mac version.

Spamihilator

A configurable Windows proxy with Bayesian learning, word, link and rule filters, plugins, training and a recycle bin. Pick it if you want to tune a classic local filter across Windows mail clients. Its latest official release is from 2022, and there is no Mac version.

POPFile

More than a spam filter: it learns any set of categories you define, then tags incoming mail so your client can file it. That remains a useful idea for enthusiasts maintaining an older setup. The official release is from 2011, and its Mac installers stop at macOS 10.12.

SPAMfighter

A Windows plug-in built around community reports: when one user marks spam, that report helps protect the network. Pick it for a supported classic Outlook or Thunderbird setup. The free edition is for home use and adds a footer to outgoing mail; Pro removes it.

SpamBayes

A flexible open-source statistical classifier that learns from mail you mark as spam or good. Pick it for an older workflow you are comfortable maintaining or for its command-line building blocks. Its official compatibility guidance still centers on Outlook 2010 and Windows 7.

Spam Reader

A focused Outlook add-in with a self-training Bayesian filter, smart allowlists and a review folder. It is the direct pick for Windows users who want filtering inside classic Outlook. After 30 days the free version adds a disclaimer to outgoing mail; Pro removes it.

EuropeanMX

A managed business gateway for inbound and outbound filtering, malware and phishing protection, IP reputation and optional archiving. Pick it when an organization needs one cloud layer in front of every mailbox. It is not a personal Apple Mail tool.

SpamHero

A gateway priced per domain rather than per mailbox, with unlimited addresses, a shared quarantine, message logs and archiving from 7 to 30 days by tier, mail bagging for 5 days when your server is unreachable, and an outbound relay on the higher plans. Pick it when you run a domain and want one filter in front of every mailbox. It filters a domain, not a person, so it cannot help on a mailbox at someone else's domain.

Postgrey

A small, specialized server tool: defer a first delivery attempt and accept senders that retry correctly. Pick it as a low-cost greylisting layer for Postfix. It does not read message content, and greylisting can delay legitimate first-time senders.For a lightweight self-hosted layer, see Klar Pro.

Anti-Spam SMTP Proxy Server

ASSP combines Bayesian and Hidden Markov filters with greylisting, DNS lists and SPF. It also controls attachments and connects to antivirus tools. Pick it when you want that depth and are ready to run a configurable SMTP proxy.For a lightweight self-hosted layer, see Klar Pro.

SmartInbox

The closest match here. SmartInbox asks an OpenAI-compatible model if an Apple Mail message belongs in Junk. Pick it if you want to write the prompt and run your own local model. The developer says active work stopped because few people were interested.

Clean Mailbox

A French gateway that filters mail for a whole domain. It blocks spam, malware, phishing, spoofing and risky attachments. It also gives admins quarantine controls. Pick it for business protection across all users. Klar solves the narrower personal inbox problem on the Mac.

Klar

Pick Klar if you read mail in Apple Mail and want a modern multilingual model that runs entirely on your Mac. No account, no cloud, nothing to hand over.