--- title: "Spam Filter: Why Is Spam Filter Necessary? | DuoCircle" description: "Spam is referred to as “Unsolicited Commercial Email”." image: "https://www.duocircle.com/images/og-default.png" canonical: "https://www.duocircle.com/blog/spam-filtering/spam-filter-why-is-spam-filter-necessary/" --- Quick Answer A spam filter is software that blocks unsolicited commercial email before it reaches user inboxes by analyzing content, headers, sender reputation, and authentication results. It is necessary because roughly 50 percent of global email volume is spam, and a meaningful share carries phishing, malware, or credential-harvesting payloads that exploit any inbox that lets them through. Filtering methods include content analysis (keyword and pattern matching), header and authentication checks (SPF, DKIM, DMARC), sender reputation scoring, blocklist (RBL) lookups, attachment scanning, and Bayesian or machine-learning classification. No filter eliminates spam entirely, but a correctly tuned anti-spam service cuts volume to a small fraction and removes the highest-risk messages from user reach. Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=undefined%2Fblog%2Fspam-filtering%2Fspam-filter-why-is-spam-filter-necessary%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=Spam%20Filter%3A%20Why%20Is%20Spam%20Filter%20Necessary%3F&url=undefined%2Fblog%2Fspam-filtering%2Fspam-filter-why-is-spam-filter-necessary%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=undefined%2Fblog%2Fspam-filtering%2Fspam-filter-why-is-spam-filter-necessary%2F "Share on Facebook") [ ](https://reddit.com/submit?url=undefined%2Fblog%2Fspam-filtering%2Fspam-filter-why-is-spam-filter-necessary%2F&title=Spam%20Filter%3A%20Why%20Is%20Spam%20Filter%20Necessary%3F "Share on Reddit") [ ](mailto:?subject=Spam%20Filter%3A%20Why%20Is%20Spam%20Filter%20Necessary%3F&body=Check out this article: undefined%2Fblog%2Fspam-filtering%2Fspam-filter-why-is-spam-filter-necessary%2F "Share via Email") ![Spam Filter](https://media.mailhop.org/duocircle/images/2021/07/spf-record-7339.jpg) _Spam is referred to as “Unsolicited Commercial Email”_. The [spam filter](/email/spam-filtering) is a type of program or _software designed specifically to block unsolicited and indiscriminate content sent over the email_. Constant nuisance created by an information system **security threat** named SPAM is not going anywhere for coming years. Spam mail titles are too catchy that one tends to read the mail and this infects the organization’s networks and information system. For security reasons, there is an urge for an effective **spam filter system**. _The spam filter is a reliable security control against adversaries_. The [job of a spam filter](/content/spam-filter/what-is-a-spam-filter-and-how-does-it-work) is to look for particular words in the email or website content based on precise filtering analysis and consequently excludes them from the user’s inbox. If we check the various published reports. > It was found that **50% of the email messages** sent globally were listed as spam. The spam filter is mandatory to safeguard the security of organizations that receive tons of content each day. Although, it is not possible to prevent tenacious spammers from junk mail completely, installing [anti-spam solutions](/email/spam-filtering) can significantly reduce the amount of spam. [![](https://media.mailhop.org/duocircle/images/2023/10/Spam-Filtering-Statistics.png)](https://media.mailhop.org/duocircle/images/2023/10/Spam-Filtering-Statistics.png) ## How To Prevent Spam Emails? **Anti-spam solutions** are of great help in one’s business if one is experiencing spam emails in huge volumes. Spam is a serious security threat as it affects every internet user directly or indirectly, and there is no real solution to spam in comparison to anti-virus software programs. _Spam emails sent by unknown senders can be filtered out effectively with a proactive Anti-spam solution_, which is a time-saving process. There are a variety of [spam filtering methods](/content/cloud-spam-filters/spam-filtering-solutions) available today, and all the methods have only one goal, and that is to **“REMOVE or STOP”** unwanted emails. A few of the ways are listed below. ### Spam Filtering By Content This is the most commonly used technique to block spam emails. The most common spam words include additional income, cash prize, and you are a winner. Such catchy words or emails need to be filtered. ### Blacklisting Certain IPs _Spammers mostly use the IP address for hacking_. In such a scenario, organizations need to [blacklist specific IP](/outbound-smtp/blacklisted-email-ip-digital-pariah-can-impact-business/) addresses. In this way, they can _prevent spam emails from those IPs_. ### Real-Time Blackhole List This real-time [blackhole list](https://www.techopedia.com/definition/25294/real-time-blackhole-list-rbl) is similar to a blacklist except that third-party enterprises maintain it. Whenever a mail comes, the filter connects it to the third party system each time to compare the sender’s address against the preset list. This outsourcing is productive in organizations where the IT staff doesn’t have enough time to spend manually on maintaining blacklists. ### Heuristic Filters _[Heuristic filters](/spam-filtering/anti-spam-filters-and-how-they-work/) are a form of content-based filters that focus on suspicious words that are commonly found in spam messages_. Frequently received suspicious words such as ‘Rolex or ‘Viagra etc. are marked high scores while the terms found in regular emails receive lower scores. As determined by the **anti-spam** application’s administrator, the filter blocks the messages containing high-scored words. ### Bayesian Filters [Bayesian Filters](/spam-filtering/anti-spam-filters-and-how-they-work/) are considered as an advanced and recent form of content-filtering methods. These filters take into practice a mathematical probability to classify the different recurring words in two separate lists, i.e., junk and legitimate. _A time span is required by Bayesian filters to continually maintain this list after analyzing the content of received emails by users_. Thus, their effectiveness is seen as long as you use them. In the first instance, you may have to delete the junk files on your own. ### DNS Anti-Spam Method _DNS lookup system looks for the Domain name of the sender that they use to identify themselves_. The system tries to verify the email address with that of a valid [MX record](/announcements/new-mx-records-dns-redundancy/). If there is no match, then the message is assumed to be junk and removed automatically by the system. This lookup will accurately reveal the domain name associated with the server and is proved to be useful in detecting spam. [![Anti-Spam](https://media.mailhop.org/duocircle/images/2021/07/spf-record-check-7340.jpg)](https://media.mailhop.org/duocircle/images/2021/07/spf-record-check-7340.jpg) ## OOP Spam Filter API In case, you are also searching for an [email spam filter](/content/email-spam-filter), then take a note of the below-given spam filter API version. It may help you to cope up with your needs. This spam filter is manufactured to filter any content exchange, whether it’s a blog, forum, or social media. The use of various tools is combined in such a way that it helps to detect the number of spam words in content in an efficient manner and not to leave any drawback. It supports the following features: ### Machine Learning Algorithm A well-trained and inbuilt [machine learning algorithm](/content/spam-filter/spam-filtering-techniques) detect whether the content is spam or not. ### Scoring Spam It follows an advanced heuristic **spam filtering method**. A score ranging from 0 to 6 is assigned to every content, and one has a higher probability considered as spam. ### Spam Word Detection _The content containing a large number of words are detected against a list of common suspicious spam words_. This list may be preset or continuously maintained by the filter depending upon the mathematical probability of received messages. ### Blacklist IPs List The screen is capable of maintaining a constant list of spammers Ips and are updated in their servers and categorized as blacklisted IP list and throw out the spam messages. ### Language Outlier Detection Algorithm This particular technique of the filter enables the analysis of language received in content and ensures that it integrates well with your expectations. It is deployed on Rapid API where you can easily find detailed information about the application. ## Conclusion Is it realistic to avoid using [spam filters](/email/spam-filtering)? Hopefully, the answer is prevalent in the article above. _It highlights the significance of using spam filters as a reliable control measure_. Not only **phishing attacks**, but spam can also exploit the information systems, causing the loss of sensitive information. _The Spam filters will also help prevent the phishing attacks attempted by adversaries_. ![Brad Slavin](https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg) Brad Slavin General Manager General Manager at DuoCircle. Product strategy and commercial lead across the email security portfolio. ## Secure your email infrastructure Protect, authenticate, and deliver. Contact our team to find the right solution. [Contact Sales](/contact/) [Explore Products](/products/) ## Related Articles [ Spam Filtering 5m A Guide On Email Gateway: What It Is And The Importance Of A Secure Email Gateway Mar 4, 2021 ](/blog/spam-filtering/a-guide-on-email-gateway-what-it-is-and-the-importance-of-a-secure-email-gateway/)[ Spam Filtering 5m Anti-Spam Filters and How They Work Jun 19, 2020 ](/blog/spam-filtering/anti-spam-filters-and-how-they-work/)[ Spam Filtering 1m CERT Advisory Symantec and Norton Critical Vulnerability Jul 6, 2016 ](/blog/spam-filtering/cert-advisory-symantec-norton-critical-vulnerability/)[ Spam Filtering 3m Cloud-Based Spam Filtering Protects Your Company Sep 10, 2018 ](/blog/spam-filtering/cloud-based-spam-filtering-protects-your-company/) ```json {"@context":"https://schema.org","@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. 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