--- title: "All About Email Filtering Service: Types Of It & How It Works | 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-gateway-service/email-filtering-service/" --- Content # All About Email Filtering Service: Types Of It & How It Works 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/) ## All About Email Filtering Service: Types Of It & How It Works [Fix Your SPF Errors Now](/content/spf-permerror) Nobody likes to be bothered by unnecessary and irrelevant things when in the middle of something important. _This becomes all the more troublesome and infuriating if such the distraction involves spammers and threats to your organization_. Emails are one of the most widely used platforms by adversaries to make spam messages reach your inbox. Hence, it is of utmost importance to ensure that you have proper [email security](/content/email-gateway-service/email-security) services that prevent such fake emails from reaching you when all you want to focus on is work! There are thousands of **email filtering services** available today that aim to facilitate a spam-free working environment for you. Enterprises across the globe seek the help of some [email gateway services](/content/email-gateway-service) or other _email protection based products to protect themselves against malware better_. ![email gateway providers](https://media.mailhop.org/duocircle/images/2019/02/email-phishing-protection.png) ### Secure Email Gateways The [email gateway definition](/content/email-gateway-service/email-gateway-definition) can be expressed as a service that enables you to make the emails received go through a virtual ‘gateway’ wherein they are scrutinized for the presence of any malware or other harmful content. _This gateway ensures that only those emails with genuine and harmless content reach your inbox and discard the ones that appear dubious_. ### How Email Gateway Works As mentioned, [email gateway solutions](/content/email-gateway-service/email-gateway-solution) protect from the attacks of adversaries that originate from emails. _The gateway scans both incoming and outgoing emails for any malicious content_ and provides the following four security features. If you take a look below at [how email gateways work](/content/email-gateway-service/how-email-gateway-works), you can see how **email filtering service** is an integral part of the whole enterprise security solutions. - **Blocking of Virus and Malware:** One percent of all emails that crowd our inboxes are emails with viruses and malware. Hence _the email gateway service comes with the provision of blocking these emails with viruses and malware content._ - **Spam Filtering:** _All email gateways give considerable focus to the deletion and handling of spam_. Since spam is where all the malicious activities begin, they take special care to filter those emails for the safety of the user. Not only does **spam filtering stop emails** from unknown sources and spammers to reach the end-user, but it also detects standard techniques used by attackers to identify them better in the future. - **Content Filtering:** This provision lets a user filter their outgoing emails to ensure that no private attachments, images, or files are sent to outsiders even by mistake. _This is like an added protective measure against **data theft** and further enhances your overall privacy and security._ - **Email Archiving:** _Email archiving is a feature that makes organizations hire different and specialized services altogether_! It is essential in making your systems function smoothly, for reducing storage space and for efficient management and handling of critical data. However, [email gateways](https://docs.oracle.com/cd/E19683-01/816-4882/mailrefer-72/index.html) these days come with this much sought after provision. ![email gateway service](https://media.mailhop.org/duocircle/images/2019/02/advanced-threat-defense.png)![email gateway service provider](https://media.mailhop.org/duocircle/images/2019/02/business-email-compromise-what-is-it.png) ### How Email Filtering Services Work Typical **email filtering services** are of two types: list-based filters and content-based filters. #### List-Based Filters List-based **email filtering** works by using a preset list of senders marked as either spammer (blacklist), trusted senders (white list), or unconfirmed and treated as suspicious (greylist). The user or an organization’s system administrator can create these lists. Based on these categorizations, _only the messages from trusted origins are allowed to enter your inbox_. #### Content-Based Filters Unlike list-based filters that block or allow emails from a particular IP address or email ID, content-based filters scan and evaluate the email contents – words and phrases in the messages – to analyze their authenticity potential for threat. Content-based **email filters** are also called rule-based filters as they review the content of email messages according to _preset rules and policies to decide whether may or may not contain a threat to the recipient_. The three main types of content-based filters are word-based filters, heuristic filters, and Bayesian filters. For individuals or organizations with a tight budget, it may not be feasible to allow a budget for a premium **email gateway service**. However, you can find yourself an [email gateway free](/content/email-gateway-service/email-gateway-free) of cost with a good bit of research and analysis. While there are many exceptional email gateway services available for a specific subscription fee, _there also exist several other decent service providers whose services are free of cost._ ##### Join the thousands of organizations that use DuoCircle --- Find out how affordable it is for your organization today and be pleasantly surprised. [Outbound SMTP - Sign Up FREE](/email/outbound-smtp)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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