--- title: "What Do Spam Filters Look For: How To Make Sure Your Marketing Campaign’s Emails Don’t End Up In The Spam Folder | 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/spam-filter/what-do-spam-filters-look-for/" --- Content # What Do Spam Filters Look For: How To Make Sure Your Marketing Campaign’s Emails Don’t End Up In The Spam Folder Spam filters look for spam-characteristic subject lines and phrases like 'Special promotion,' grammar and spelling errors, sender and ESP reputation including blacklisted IP addresses, link-heavy content with little meaningful text, and suspicious images. Email marketers who avoid these triggers when composing campaigns improve the chance their messages reach recipients' inboxes instead of the spam folder. [ Talk to an Expert → ](/contact/) [ See what we make ](/products/) ## What Do Spam Filters Look For: How To Make Sure Your Marketing Campaign’s Emails Don’t End Up In The Spam Folder [Spam Filtering - Sign Up](/email/spam-filtering) _Spam is a significant problem of today’s digital age bringing financial damage to organizations and annoying individual users_. A spam filter plays a significant role in the success of email campaigns. So, [what is a spam filter and how does it work](/content/spam-filter/what-is-a-spam-filter-and-how-does-it-work)? A spam filter is a software tool that _can identify unsolicited and unwanted email (spam) and block it from getting into the recipient’s inboxes_. A **spam filter** scans through an incoming message based on specific criteria and determines whether it’s spam or not. So, what are those criteria? What do spam filters look for in an email? Here’s finding out the answers. ![spam filter](https://media.mailhop.org/duocircle/images/2021/02/mail-gateway-server.png) ### What Do Spam Filters Look For In Emails? Installed [spam filters](/content/spam-filter) might look for various anomalies and signs in an incoming email message indicative of spam. They are: - **Topics Characteristic To Spam**: _Spam email subject header and contents will have specific characteristics_. They are detected by analyzing the words used in them. For example, words and phrases such as ‘Special promotion,’ ‘100% free,’ ‘Lifetime offer,’ and ‘Earn extra cash’ indicate a high possibility of spam. - **Grammar And Spelling Errors**: Poor grammar and spelling are very common in spam emails. As a result, filters often classify poorly written messages as spam. Although AI writing tools can generate grammatically correct content, an advanced [AI detector](https://gptzero.me/) can still identify such emails based on language patterns and writing behavior.​ - **Sender’s Reputation**: This is a sure way to determine if an email is a spam message. Various sources give information about the [reputability of a sender](https://sendgrid.com/blog/5-ways-check-sending-reputation/). Emails from blacklisted sender IP addresses can be readily rejected. - **ESP Reputation**: _Reputed ESPs usually won’t transport spam_. Hence, if the email is not from a trustworthy ESP, there is a high chance that the filter suspects spam. - **Undue Importance To Links**: Sometimes, the email content is only a link, and there is not much text to read. This is one [way to detect it](https://www.itgovernance.co.uk/blog/5-ways-to-detect-a-phishing-email). It means the sender only wants to take you to their website. Even if there is some text, it mostly won’t make much sense. - **Email Messages With Suspicious Images**: _Messages with more images and hardly any meaningful text indicate spam_. It shows a lack of dedication in communicating anything. Instead, the spammer only needs to capture the attention. ### Criteria In Paid Vs. Free Spam Filters The criteria used by a [spam filter service](/content/spam-filter/spam-filter-service) on incoming emails are more or less the same in paid spam filters and free ones like [spam filter Gmail](/content/spam-filter/spam-filter-gmail). And both versions make use of effective [spam filtering techniques](/content/spam-filter/spam-filtering-techniques). The differences could be with advanced features, capacities, and reliability. Even if one only needs a free version, one can compare multiple options and choose the [best free spam filter](/content/spam-filter/best-free-spam-filter) as per one’s requirements to prevent spam messages from landing in the inbox. Answering the question “What do spam filters look for?” is especially useful to those that need to send many emails to people. They can take care while composing the emails to ensure they don’t violate any of the criteria [spam filtering solutions](/content/spam-filter/spam-filtering-solution) apply to incoming emails. That way, one can make sure the sent emails are delivered to the recipient’s inbox. ![spam filter service](https://media.mailhop.org/duocircle/images/2021/02/mail-gateway-service-1.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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