SpamSieve

About

SpamSieve uses Bayesian spam filtering to keep spam out of your inbox. It learns and adapts to your mail, offering personalized filtering that aims to block nearly all spam without putting good messages in the junk mailbox. It works with IMAP, Exchange, and POP accounts, and you can control it from Apple Mail, Outlook, Airmail, MailMate, GyazMail, and more. It can also be used alongside your mail provider's junk filter to catch more spam and rescue good messages the server filter caught.

SpamSieve automatically maintains an allowlist so messages from previous correspondents are never marked as spam, and it integrates with your contacts. You can add a blocklist to stop spam from particular addresses, and customize both lists with your own rules using criteria such as regular expressions. It decodes obfuscated messages, looks inside attached images and documents, and color-codes how spammy each message is so you can check borderline cases. It also tracks its accuracy and your good and spam message counts over time.

SpamSieve preserves your privacy: it does not need your mail account login, does not transmit your mail data anywhere, and does all processing on your Mac. It can also keep spam off your iPhone and iPad, and lets you turn off new-mail notifications in your mail client so you're notified only about new non-spam messages. A log shows everything SpamSieve did and why, and optional AppleScripts allow deeper customization. It requires macOS 10.13 High Sierra through macOS 27 Golden Gate and an e-mail client.