SpamSieve 2.9 review: A must-have spam filter for your Mac email client

SpamSieve learns from the email messages you receive, making it a very accurate spam filter.

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At a Glance
  • C-Command SpamSieve 2.9

Oh, spam. There is so much of it. Some estimates say that 90 percent of email sent around the world is spam. Sometimes it's hard to sort the wheat from the chaff; or the ham from the spam.

It's been a plague since the earliest days of the Internet. Whether it's spam that contains attachments—which, if opened, could hijack your computer (though most often, these attachments carry Windows malware)—or phishing emails that try to trick you into entering your bank or Apple ID credentials on dodgy websites, spam is both an annoyance and a danger.

There are several ways you can block spam. If you use Gmail or iCloud for your email, there are built-in spam filters. In Gmail you can view your spam to check for any legitimate email that has been filtered as noxious, but you can't do this with iCloud. Much of the spam that iCloud gets is simply deleted, and you don't even know about it.

If you have your own domain name and host your email, then you can control how a server-side spam filter works. But I find that when the server filters the spam, I forget to check for legitimate emails. I get lots of contacts from readers, and it's annoying to find that many of these emails get tossed in the spam folder. And Apple Mail—the email client I use—isn't great at filtering spam.

Years ago I decided that I prefer using software on my Mac to filter spam. C-Command Software's $30 SpamSieve has been around since 2002 and is hands down the best spam filtering software for Mac. Unlike the brute-force filters on servers, SpamSieve learns from your email. If you get lots of emails that contain certain words, SpamSieve learns that these are normal, and sends them to your inbox. However, if spam gets through, you just select one or more messages and press a keyboard shortcut to tell SpamSieve that they are spam; the app learns from that too. And it's incredibly accurate. Here are my SpamSieve statistics, since the last time I did a clean install on my Mac, about a year and a half ago:


The SpamSieve window is a low-key dialog that lets you access preferences, a log, statistics, and more.

SpamSieve has a whitelist of your contacts and people you have sent email to, a blacklist that automatically blocks email from senders you've flagged, and its Bayesian analysis makes it incredibly accurate. I still get some spam in my inbox, but no more than a couple of messages a day.


SpamSieve has blocked more than 19,000 spam emails, with 99.4 percent accuracy.

After you install SpamSieve—which works with Apple Mail, Outlook, Airmail, Postbox, and many other email clients—you don't ever see the app. In fact, there is no SpamSieve window, only some settings dialogs that you can display in Mail, for example, by choosing Message > SpamSieve - Open Window.

SpamSieve launches in the background when you open your email app, and you can control its main features—telling the app that given messages are spam or good email—from the keyboard, or from a menu. This app works so well that, over time, you almost forget about it. And those two keyboard shortcuts—Train as Good and Train as Spam—become second nature.

There's a lot more: detailed logs, optional coloring to indicate how spammy messages are, custom rules, remote training, and more. And if you keep a Mac with SpamSieve running, you can even keep spam from flooding your iOS device's inbox.

Filtering spam on my Mac makes my life easier, and SpamSieve is so accurate and so easy to use, that it's one of my 10 essential Mac utilities.

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At a Glance
  • C-Command SpamSieve 2.9

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