SpamSieve: Mac Software Pick

Courtesy of C-Command

SpamSieve from C-Command is by far one of the most powerful spam filtering systems available for the Mac. SpamSieve works with the most popular email clients, including Apple Mail, Airmail, Outlook, Gmail, and iCloud. It will also work with just about any mail server, including those using POP, IMAP, or Exchange protocols.

SpamSieve makes use of Bayesian spam filtering techniques, and whitelists and blacklists that are easy to manage; it even displays just how spammy it thinks an incoming message is.

What We Liked

  • Runs on your Mac, not on a remote server somewhere.
  • Highly-adaptive Bayesian filter that quickly learns from new spam messages.
  • Works with just about any mail provider service.
  • Maintains a whitelist to guarantee message delivery.
  • Maintains a blacklist to keep known spammers at bay.

What We Didn't Like

  • Must be trained by each user to learn what spam is.
  • Training time can be long, depending on the amount of spam a user receives.

SpamSieve has been around for quite a while. We remember using it with Eudora on our Mac, back when OS X Jaguar was being mispronounced by Steve Jobs. In all that time, SpamSieve has been kept up to date and remains one of the best anti-spam choices you can make for your Mac.

SpamSieve runs on your Mac as a preprocessing plug-in for your mail client. Because of how SpamSieve works, running its filtering routines on incoming mail before the actual mail client gets the data, SpamSieve can remain your spam filtering system even if you change mail clients. Getting tired of Apple Mail, and thinking about moving to a competitor, such as Outlook? Not an issue for SpamSieve. Just install the SpamSieve plug-in for the new mail client and you're good to go.

Installing SpamSieve

Installation is a three-step process, starting with the basics of dragging the SpamSieve app to your /Applications folder.

Once it's installed, you need to instruct your mail client to use SpamSieve. The method for installing the SpamSieve plug-in differs slightly from client to client, but there's nothing difficult about the process.

The final step is to train SpamSieve about what is and isn't spam. The process starts when your mail client receives a message. SpamSieve will intercept the message, examine the message details, and then move the message to either your mail client's inbox or a spam folder. Your job is to go through the spam folder and mark the messages that aren't spam; you'll also need to check your inbox, to see if SpamSieve missed any messages that are spam, and mark them as such.

Over time, SpamSieve will learn which is which, and become very accurate at detecting and correctly processing spam for you. If you would like to speed up the training process, you can use any spam messages you already have within your mail client, and mark those as spam using SpamSieve.

Using Web-Based Mail Systems

Web-based email systems, such as Gmail, Yahoo!, and iCloud, can also be used with SpamSieve, although not directly through a web interface. Instead, you'll need to set up your current mail client to access your web-based mail using the POP, IMAP, or Exchange protocol. Almost all of the popular webmail systems provide one or more of these standard mail protocols as an alternative for accessing their mail servers.

Once you have the webmail accounts set up in your mail client, you can use SpamSieve just like you would for any standard mail system.


SpamSieve can maintain a whitelist, which is a list of email addresses from which you're always willing to receive email. SpamSieve can use your Contacts list as its whitelist source. You can also have the whitelist include anyone you've sent email to, on the premise that you wouldn't send messages to spammers.


SpamSieve usually refers to this as a blocklist; both names seem to be used on occasion. No matter what you call it, a blacklist is a list of rules that define a message as originating from a spammy source.

The rules can be as simple as the sender’s address is equal to Or it can be far more complex, with rules that include looking at the message content for specific words or patterns. For example, while we were testing SpamSieve, we were receiving messages with the subject line Gift – Cards. SpamSieve was good enough to add any message with that unusual subject line to the blocklist.

By using rules to control the blocklist, SpamSieve allows you to create rules that work even when the sender’s name or address is constantly changing.

Final Thoughts

We found SpamSieve easy to set up. Its spam learning system was easy to train, and much quicker and more accurate than Apple Mail's built-in spam filtering system. In fact, Apple Mail and SpamSieve make very powerful partners for fighting spam.

If you have spam problems, and really, who doesn’t, and your mail client is having a problem accurately separating spam from normal mail, give SpamSieve a try. It may be just the app you need to keep spam at bay.

SpamSieve is not free but a demo is available.