Billions of emails are sent between senders and recipients every day. Secure email gateways (SEG) protect organizations of all sizes from cyber threats like phishing attacks and ransomware. They scan incoming and outgoing messages to ensure no malicious content enters your employees’ inboxes or leaves your business networks. They also feature centralized admin controls and automated reports to save administrators time.
Email Gateway Architecture
A Secure Email Gateway (SEG) is a server that analyzes all incoming and outgoing emails before they reach an organization’s internal email servers. It acts as a firewall for emails and prevents malware, phishing attacks, and other cyber threats from spreading across the network. An email gateway architecture uses multiple technologies to protect organizations from email-based cyber attacks. Typically, it redirects both inbound and outbound emails via a proxy and then sanitizes them to detect red flags that indicate a malicious message. It can also analyze the contents of an email to prevent sensitive data from leaving the organization’s network. The most important function of a secure gateway is spam filtering. It uses a combination of various filters like list-based, word-based, heuristic filtering, and Bayesian filters to detect the specific patterns spammers use in their messages. It can also block emails with malware attachments and suspicious links. An SEG can also use content filtering to prevent internal actors from exfiltrating data using steganography techniques. This involves removing metadata and comments from documents to ensure that the only data sent is what the recipient expects. It can also sanitize image files to ensure that only the file itself is sent, not its thumbnail or any hidden text. Moreover, it can also check that outgoing messages meet security policies and automatically encrypt documents containing sensitive information.
Email gateways are an essential part of any security architecture. They protect users and their devices against email-borne threats such as spam, phishing attacks and malware. They prevent these attacks from reaching their intended recipients and compromising devices, credentials or sensitive data. An email security gateway works by filtering and scanning incoming and outgoing emails to ensure they are risk-free before being sent to their recipients. This is done using various technologies, including anti-virus, content and phishing protection, malware detection, quarantine management, track and trace and an admin dashboard. A secure email gateway can be deployed as an on-site virtual appliance or a cloud service. Typically, on-site email security gateways require companies to install and maintain hardware. However, many vendors now offer email security gateways as a public cloud-based service so that the company’s email traffic passes through the vendor’s infrastructure instead of an on-site appliance. A cloud-based email security gateway offers benefits such as easy deployment, scalability and a low cost of ownership. Some vendors also offer add-on security capabilities such as email encryption. This provides extra security for users whose devices are outside the organization’s control, such as employees using bring-your-own-device (BYOD) laptops or smartphones. These additional features increase the overall security of an email security gateway.
Email gateways fortify an organization’s email network by providing the first line of defense against cyber threats. They monitor incoming and outgoing emails for red flags that could indicate a threat and protect users from spam, ransomware, and other malware. The gateways also provide tools like phishing protection, content filtering, and email archiving. An email gateway can be deployed either on-premises or as a cloud service. Companies that deploy on-premises appliances are responsible for hardware and software maintenance and connectivity to their internal mail servers. However, cloud services have the scalability to maintain performance even during peak usage. The scalability of an email gateway is especially important when dealing with large numbers of employees. An inability to handle this volume can lead to significant downtime and the risk of a security breach.
Moreover, many attacks are becoming more sophisticated and may be undetected by standard security measures. This is why most email gateways provide post-delivery protection. This feature detects and blocks unknown threats that might not be detected during inline inspection, such as zero-day threats. Most gateways also support DMARC (Domain-based Message Authentication, Reporting, and Conformance), which helps prevent spoofing by blocking emails that don’t pass this test.
Email gateways offer predelivery protection by blocking email-based threats before they reach an on-premise, Office 365, or G Suite mail server. They use various technologies to scan outbound and inbound emails for malicious content and implement rules for which emails may leave or enter an organization’s email network. Some gateway products are email server-specific, such as those that work with Exchange or Domino servers. Others install a hardware appliance on-site, with inbound and outbound email traffic routed through the device for analysis and filtering. These gateways are considered a strong first line of defense against email-based cyber threats. Most gateways can detect spam by using multiple filters. They also employ various methods to weed out malicious attachments, including real-time sanitization and seeing macros and scripts in files. Most gateways can detect embedded URLs in phishing attacks and rewrite or block them. They can also sanitize and block links in images. Most gateways also have features that limit or block the ability to forward emails, and they can also scan outgoing email addresses for spoofed domains. Some gateways will encrypt email messages, but this is usually an add-on capability requiring a separate subscription and often involves additional administrative tasks. These types of gateways are called secure email gateways, and they can prevent malware, phishing attacks and other unwanted email from reaching employee devices and potentially compromising devices, user credentials or sensitive data.