Top Free Spam Filters for Windows

Physical mailbox filled with letters and junk mail
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Protect your inbox from spam, as well as incoming viruses and malware, with a good spam filter. Some of the best anti-spam filtering tools for Windows are completely free. Try these to rid your inbox of all your junk mail efficiently, and save your time and attention for more important matters.

Spamihilator

Screenshot of Spamihilator on Windows

Clayton Kroh

What We Like

  • Plenty of plug-ins available to expand functionality.

  • Clean interface that's not overcrowded with features.

What We Don't Like

  • No option to classify or categorize nonspam mail.

  • No support for remote web-based administration.

Spamihilator is an attractive, easy-to-use anti-spam tool that works with any email client and, thanks to Bayesian filters, has a good detection rate. It removes more than 98 percent of spam emails before they appear in your inbox. Spamihilator is highly configurable and works with both 32-bit and 64-bit Windows PCs.

Spamfence

Screenshot of eXpurgate
Heinz Tschabitscher

What We Like

  • Integrated virus protection adds extra security.

  • Keeps your primary email account 100 percent junk free.

What We Don't Like

  • Awkward to set up and use.

  • Adds an annoying subject header to each message.

Spamfence is an easy but highly effective spam and virus filtering service. It uses eXpurgate, the service behind Spamfence, to protect your inbox. Spamfence's only real shortcoming is that it relies on forwarding and requires two different email accounts.

SpamExperts

What We Like

  • Flexible pricing plans available for different levels of need.

  • Control panel is very mobile friendly.

What We Don't Like

  • Customer service is based in Europe and operates on European time.

  • Sometimes gets overzealous and marks things as spam that aren't spam.

SpamExperts identifies and eliminates spam effectively, thanks to its real-time database and user synchronization. It works without additional configuration, and with any email program and just about any email account. SpamExperts can be deployed locally or run from the cloud, and it monitors incoming and outgoing emails. With its acquisition by SolarWinds MSP, SpamExperts gained an intuitive, easy-to-set-up user interface. Also as a result of the acquisition, SpamExperts is no longer free, but a free trial is available.

K9

What We Like

  • Advanced settings to track session statistics.

  • Add custom sound notifications.

What We Don't Like

  • No technical support.

  • Takes a little time and work to properly configure.

K9 is a wonderfully precise, easy-to-use, and fast-learning Bayesian spam filtering tool. It's a pity this gem only works with POP accounts and lacks remote administration. Although no longer in development, K9 still works well for many Windows users.

G-Lock SpamCombat

Screenshot of G-Lock SpamCombat software

Clayton Kroh

What We Like

  • Deletes spam on the server before it makes it into your email.

  • Easy to recover deleted messages.

What We Don't Like

  • Not available for Mac or Linux.

  • Full version requires you to purchase a license after 60 days.

G-Lock SpamCombat is a comprehensive and competent Bayesian spam filter that can make use of DNS blacklists. G-Lock SpamCombat uses email filters to prevent spam from making it to your inbox: Complex Filter, Whitelist, Blacklist, HTML validator, DNSBL filter, and the Bayesian filter. This program works with POP3 and IMAP accounts.

MailWasher Free

Screenshot of MailWasher software

Clayton Kroh

What We Like

  • Works well on iOS and Android mobile devices.

  • Doubles as an email client.

  • View messages from multiple accounts in one place. 

What We Don't Like

  • Can't block messages based on country of origin.

  • Customer support has poor reviews.

MailWasher Free is a flexible, elegant, and effective spam filtering solution. MailWasher Free only works with one account and lacks the blacklist and server-based filtering found in MailWasher Pro. However, the free version lets you preview emails on the server and delete them there. This real-time spam filter service works with POP3, IMAP, AOL, Gmail, and other clients.

SpamWeasel

Screenshot of SpamWeasel

Clayton Kroh

What We Like

  • More features than most free alternatives.

  • Registration is no longer required.

What We Don't Like

  • Making custom filters requires some programming knowledge.

  • No customer support beyond the online user manual.

With a full-fledged scripting language for filters, SpamWeasel is one of the more powerful free anti-spam tools. This easy-to-install filter works in a POP3 environment across any connection. Each message is ranked by the number of penalty points it accrues according to the program's rules. While the program works great out of the box, writing new filters isn't easy.

Cactus Spam Filter

Screenshot of Cactus Spam Filter

Clayton Kroh

What We Like

  • Training feature that automates the filter configuration process.

  • Never automatically deletes messages.

What We Don't Like

  • Using it with Gmail or an SSL connection requires some extra setup.

  • No mobile support.

Cactus Spam Filter is an easy-to-use and precise spam filter that only works with POP3 accounts. When you download and install the Cactus Spam killer, it starts protecting your inbox right away. No additional settings in your email client are necessary. Cactus Spam Filter is compatible with Windows 7 and older operating systems.