--- title: "Get To Know What Is A Spam Filter And How Does It Work | DuoCircle" description: "Join the thousands of organizations that use DuoCircle Find out how affordable it is for your organization today and be pleasantly surprised.Interested in" image: "https://www.duocircle.com/images/og-default.png" canonical: "https://www.duocircle.com/content/email-spam-filter/what-is-a-spam-filter-and-how-does-it-work/" --- Content # Get To Know What Is A Spam Filter And How Does It Work Join the thousands of organizations that use DuoCircle Find out how affordable it is for your organization today and be pleasantly surprised.Interested in [ Talk to an Expert → ](/contact/) [ See what we make ](/products/) ## Get To Know What Is A Spam Filter And How Does It Work [Spam Filtering - Sign Up](/email/spam-filtering) In this digital age, most email marketing experts are aware of **email spam filters**. They craft their messages tactically to ensure an unrestricted delivery mechanism. With sophistication, _spam filters have become more robust and smarter than they used to be_. Let’s try to know more about what is a spam filter, and how does it work. ![spam filtering solutions](https://media.mailhop.org/duocircle/images/2020/11/gateway-spam.png) ### What Is A Spam Filter? _Spam filters offer intelligent mechanisms to identify and restrict unwanted, unsolicited emails, otherwise known as spam emails_. With a spam filter, users can prevent such emails from entering their inboxes. Most of the time, ISPs deploy these tools to ensure that spam emails are not distributed. Startups and established organizations alike incorporate [spam filtering solutions](/content/email-spam-filter/spam-filtering-solutions) to protect their networks. In the information age, spam filters find their utility in both [inbound and outbound emails](https://powerdigitalmarketing.com/blog/the-important-difference-outbound-email-vs-inbound-email/#gref). Though large organizations can have sophisticated paid **spam filter services**, individual users can rely on the [free email spam filters](/content/email-spam-filter/free-email-spam-filter) included in their email account, such as [spam filter Gmail](/content/email-spam-filter/spam-filter-gmail) that can provide necessary **protection from spam**. ### How Does A Spam Filter Work? _Spam filters subject each of the email messages to several algorithms_. This process is termed as the ‘**heuristics**‘ method. The chance of an email being spam is assigned with a particular numerical score by each rule. When this score crosses a given limit, the spam filter blocks the email, marking it as vulnerability. Now, the point is, _[what do spam filters look for](/content/email-spam-filter/what-do-spam-filters-look-for) in an email?_ Depending on the criteria, spam filters can be of various types. #### Header Filters These _spam filters scrutinize the email header’s source_, identifying spammers’ email addresses or other suspicious information. #### Content Filters One of the most extensively deployed [spam filtering techniques](/content/email-spam-filter/spam-filtering-techniques), content filtering, examines the message content in emails. _They scan each word to detect vulnerabilities_. #### Rule-Based Filters These days, organizations prefer customizing rules so that emails from particular senders or the ones containing certain words get filtered out. These filters are termed as ‘[rules-based filters](https://ieeexplore.ieee.org/document/6086218).’ #### Block-list Filters This kind of [email spam filter](/content/email-spam-filter) can block emails that come from suspicious IP addresses. Besides, some of the advanced mechanisms also _check the reputation of the respective IP address_. Now, as an email marketer, you might be wondering [how to avoid spam filters](/content/email-spam-filter/how-to-avoid-spam-filters). To accomplish this goal, make sure you are unique with your subject line and email body, so the emails will not be interpreted as spam. While most organizations are on the lookout for the [best free spam filter](/content/email-spam-filter/best-free-spam-filter), no single strategy can completely **weed out spamming**. Some enterprises go for a tool that is paid or with a considerable reputation to get comprehensive protection against online vulnerabilities. Competent marketers have demonstrated the process of turning an **email spam filter** to their advantage. Once they are well-versed with how these filters work, they can strategically draft their emails to avoid being dubbed as a spammer. ![email spam filter](https://media.mailhop.org/duocircle/images/2020/11/spam-gateway.png) ##### Join the thousands of organizations that use DuoCircle --- Find out how affordable it is for your organization today and be pleasantly surprised. [Spam Filtering - Sign Up](/email/spam-filtering)Interested in our Partner Program for MSPs and VARs? Visit Our [MSP Partner Program](/msp-partner-program). ## Ready to talk? Same-day response from someone technical. We tell you yes or no quickly. If yes, we get to work. 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