--- title: "Understanding the relevance of Secure Email Gateways (SEGs) | DuoCircle" description: "Understanding the relevance of Secure Email Gateways (SEGs)." image: "https://www.duocircle.com/images/og-default.png" canonical: "https://www.duocircle.com/blog/email-hosting/understanding-the-relevance-of-secure-email-gateways-segs/" --- Quick Answer A Secure Email Gateway (SEG) is an inline security layer that filters inbound and outbound mail before it reaches user mailboxes. Core functions: anti-spam filtering, malware and attachment scanning, URL rewriting and time-of-click protection, content filtering for DLP, and SPF/DKIM/DMARC enforcement. Common SEG products include Proofpoint, Mimecast, Barracuda, and Cisco Secure Email; Microsoft Defender for Office 365 provides comparable capabilities native to Microsoft 365\. Limitations: SEGs struggle with internal account-takeover phishing (mail from a compromised legitimate mailbox passes inspection), advanced social engineering with no malicious payload (CEO fraud, BEC), and zero-day URLs that resolve cleanly at delivery and weaponize after click. Modern deployments pair an SEG with API-based post-delivery detection (ICES tools) that can claw back malicious mail after it lands. Understanding the relevance of Secure Email Gateways (SEGs) Your browser does not support the audio element. [ Download episode](https://media.mailhop.org/duocircle/images/2024/08/Understanding-the-relevance-of-Secure-Email-Gateways-SEGs.mp3) Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=undefined%2Fblog%2Femail-hosting%2Funderstanding-the-relevance-of-secure-email-gateways-segs%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=Understanding%20the%20relevance%20of%20Secure%20Email%20Gateways%20%28SEGs%29&url=undefined%2Fblog%2Femail-hosting%2Funderstanding-the-relevance-of-secure-email-gateways-segs%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=undefined%2Fblog%2Femail-hosting%2Funderstanding-the-relevance-of-secure-email-gateways-segs%2F "Share on Facebook") [ ](https://reddit.com/submit?url=undefined%2Fblog%2Femail-hosting%2Funderstanding-the-relevance-of-secure-email-gateways-segs%2F&title=Understanding%20the%20relevance%20of%20Secure%20Email%20Gateways%20%28SEGs%29 "Share on Reddit") [ ](mailto:?subject=Understanding%20the%20relevance%20of%20Secure%20Email%20Gateways%20%28SEGs%29&body=Check out this article: undefined%2Fblog%2Femail-hosting%2Funderstanding-the-relevance-of-secure-email-gateways-segs%2F "Share via Email") ![Secure Email Gateways](https://media.mailhop.org/duocircle/images/2024/08/spf-validator-2.jpg) [Secure Email Gateways (SEGs)](/content/email-gateway) are like your email infrastructure’s personal security guards. They ensure only safe and legitimate emails go out from your company, keeping it protected from [email-based attacks](https://www.prnewswire.com/news-releases/conversation-hijacking-up-70-and-1-in-10-email-based-attacks-are-now-business-email-compromise-302174802.html). The overall practice of deploying SEGs prevents the distribution of malware and phishing attempts through emails, instills **trust in your clients and prospects**, helps you stay compliant with industry standards, and, most importantly, wards off litigations and financial damages. This blog revolves around understanding how SEGs work against email threats and what their limitations are. ## What are Secure Email Gateways? By definition, Secure Email Gateways are a set of [email security](/) tools, parameters, and protocols that filter emails for suspicious and potentially malicious messages. Most SEG combinations offer at least four **essential security features**, virus and malware blocking, [spam filtering](/email/spam-filtering), content filtering, and email archiving. Today, SEGs have become an integral part of organizations that have a heavy flow of **exchange of emails**. So, whenever an email comes or goes out of your company’s zone, it gets checked by SEG tools first. If any red flags are spotted, the email doesn’t get delivered. These tools usually detect just the **traditional signs** of phishing emails and not the contemporary ones, including [social engineering](/phishing-protection/social-engineering-is-a-growing-threat/) tactics. The global market for Secure Email Gateways was valued at [$3,636.29 million in 2022](https://www.marketresearchguru.com/global-secure-email-gateway-market-24340005). It is projected to grow at a [compound annual growth rate (CAGR)](https://www.investopedia.com/investing/compound-annual-growth-rate-what-you-should-know/) of 11.07% during the forecast period, reaching **approximately $6,826.0 million by 2028**. Many industries, including telecom, IT, healthcare, government, and finance, are using Secure Email Gateways to improve their email security. In 2023, the [finance and healthcare sectors](https://www.cnbc.com/2024/02/29/change-healthcare-cyberattack-has-caused-financial-mess-for-doctors.html) experienced a significant rise in malicious emails bypassing SEGs, with increases of [84.5% and 118%](https://www.businessresearchinsights.com/market-reports/secure-email-gateway-market-107390) compared to 2022\. These findings underscore the relevance of SEGs in email security. ## The use of artificial intelligence and machine learning in SEGs _Many Secure Email Gateways have already gone ahead and integrated artificial intelligence and machine learning capabilities and are actively using them_. While the key industry players have already integrated these, the technology, on the whole, is still evolving; hence, there is a big room for improvement in **SEGs functionalities and abilities** post the integration of artificial intelligence and [machine learning](https://www.ibm.com/topics/machine-learning). This is how these modern technologies are currently being used in SEGs- ### Advanced threat detection By linking SEGs with [artificial intelligence](/email-services/ai-in-email-marketing-how-artificial-intelligence-is-changing-the-way-of-traditional-email-marketing/) and machine learning, they are now capable of recognizing specific patterns in email behavior by rummaging through vast amounts of data. What’s even more impressive is that all this can happen in real-time before the threat reaches the user’s inbox or leaves your outbox. All this is based on the simple concept of keeping a tab on **patterns and identifying anomalies**. ### Behavioral analysis AI and ML monitor user behavior to detect unusual activities. If an **email behavior deviates** from the norm (e.g., unusual login times or access from different locations), the system can flag it as suspicious ### Automated threat response Now that SEGs are empowered with artificial intelligence and machine learning, it is possible to take immediate action on [malicious emails](https://www.cnbc.com/2023/11/28/ai-like-chatgpt-is-creating-huge-increase-in-malicious-phishing-email.html) by **quarantining or blocking** them without having to employ a person to do it manually. ## How do Secure Email Gateways work? They generally operate using either of the following methods- [![Secure Email Gateways](https://media.mailhop.org/duocircle/images/2024/08/SMTP-email-server-3334.jpg)](https://media.mailhop.org/duocircle/images/2024/08/SMTP-email-server-3334.jpg) ### DNS MX record SEGs position themselves on the travel path of an email. They do this by updating your company’s [MX record](https://en.wikipedia.org/wiki/MX%5Frecord) to point to the SEG. This way, all the inbound email traffic will be routed to SEGs so that they can run checks before forwarding them to the **intended inbox**. ### API integration APIs let **users automate and streamline** the flow of work by allowing external verifications to read and edit emails. SEGs use APIs to keep an eye on emails after they reach an employee’s inbox. With [API integrations](https://www.geeksforgeeks.org/what-is-api-integration/), an SEG can also monitor and protect outgoing emails and remove harmful emails that were delivered before being flagged as malicious. ## The limitations of Secure Email Gateways Secure Email Gateways are capable of preventing many email-borne threats. However, they do hold the following limitations, too- ### Evasion techniques SEGs aren’t fully capable of dealing with sophisticated and **modern evasion techniques**, including exploiting [polymorphic malware](https://cyware.com/news/beware-ai-generates-a-truly-polymorphic-malware-blackmamba-d3599eb7), obfuscation, and [zero-day attacks](https://www.darkreading.com/application-security/attackers-have-been-leveraging-microsoft-zero-day-for-18-months). [![Prevent Malware](https://media.mailhop.org/duocircle/images/2024/08/dmarc-report-service-1.jpg)](https://media.mailhop.org/duocircle/images/2024/08/dmarc-report-service-1.jpg) ### Delayed detection Some potentially fraudulent emails become detectable or active after they are delivered to the intended recipient. In such cases, [post-delivery protection](/email-services/what-is-post-delivery-email-protection-and-why-it-is-crucial/) tools do the job of detecting them; however, sometimes damage is done before that. Advanced threats may require **continuous monitoring** and later analysis, which can also delay response times. ### False positives and negatives _The accuracy of these tools is not 100%, leaving a gap for false positives and negatives. False positives mean genuine emails get flagged as suspicious, disrupting the flow of conversation and operations_. On the other hand, false negatives mean [illegitimate emails](https://www.linkedin.com/pulse/illegitimate-emails-protect-yourself-indigo-it-limited) go undetected and bypass the **security filters**. ### Demands heavy resource Detecting sophisticated threats often needs a lot of computing power. _For instance, running and analyzing attachments in a secure ‘sandbox’ environment can be very resource-heavy, making it difficult to handle large volumes of emails_. Similarly, methods like heuristic and behavioral analysis require significant processing, which can slow down **email delivery**. ### Requires threat intelligence These tools require updated threat intelligence. If updates are delayed or the [threat intelligence](https://thehackernews.com/2024/07/cyber-threat-intelligence-illuminating.html) data is incomplete, then results won’t be accurate. So, SEGs require regular updates of **databases and algorithms**. ### Complex configurations It’s complicated to ensure **threat detections** work perfectly because managing and configuring security policies takes time and effort. Additionally, integrating SEGs with other security tools to ensure complete protection can be difficult. ### Human factor We can’t overlook the fact that humans have the ability to make illegitimate content look legitimate without **triggering tools** that work to catch traditional red flags. This means that the words used by [threat actors](https://thehackernews.com/2024/07/tag-100-new-threat-actor-uses-open.html) can seem absolutely harmless to SEGs. Such emails bypass tools as well as trick even **well-trained users**. ## Final words While no tool is 100% accurate and effective in warding off threats, **securing your emails** with the combination of Secure Email Gateways and [DMARC](/resources/what-is-dmarc) can fortify your defenses, making it harder for [malicious actors](https://www.usnews.com/news/business/articles/2024-07-20/8-5-million-computers-running-windows-affected-by-faulty-update-from-crowdstrike) to attempt phishing and spoofing in your company’s name. So, if you are interested in learning more about DMARC, [get in touch with us](/contact). ## Topics DMARCemail security ![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 [ Email Hosting 3m How do we fix the custom domain configuration problems for Azure Email Communication? Nov 29, 2024 ](/blog/email-hosting/fix-custom-domain-configuration-issues-azure-email-communication/)[ Email Hosting 3m Fixing custom domain configuration problems for Azure Email Communication Services Nov 1, 2024 ](/blog/email-hosting/fixing-custom-domain-configuration-problems-for-azure-email-communication-services/)[ Email Hosting 14m Inbox Wars: Winning with Powerful SMTP Email Hosting Apr 7, 2026 ](/blog/email-hosting/inbox-wars-winning-with-powerful-smtp-email-hosting/)[ Email Hosting 17m SMTP Service: The Best Email Providers for Secure Communication Mar 4, 2025 ](/blog/email-hosting/smtp-service-the-best-email-providers-for-secure-communication/) ```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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