Securing email servers is crucial to protect sensitive data and confidential communication. Best practices such as encryption, access controls, SPF, DKIM, DMARC, TLS and SSL, email filtering, and multi-factor authentication are essential to mitigate the risks of email-related security breaches.

This article covers the best practices for securing email servers.

Securing Email Servers: An Overview

A secure email server is a way to protect your company’s data from hackers and other threats. When you store your emails on an external server, you are vulnerable to information theft, viruses and other attacks that could compromise your business.

When you use a secure email server, you can ensure that your data is protected and that it is only accessible to employees with the correct permissions.

You also have more control over how the email service operates by adjusting settings such as spam filtering and virus scanning.

Ensuring Email Server Security: Why Securing Email Server is Critical?

Email security is a major concern for every business. The following statistics on email-based threats are alarming. They all demonstrate why securing email servers should be a key priority for every firm.

Cybercrime has surged by 600% since the start of Covid-19, putting emails and internet data at more risk than previously.
Malicious actors’ most popular method of assaulting enterprises is phishing, and they created roughly 6.95 million phishing pages in 2020.
Email security has been named the top IT security project for 2021, according to the 2021 Email Security Benchmark Report.
According to IC3, BEC (Business Email Compromise) assaults are the most expensive, resulting in a $1.8 billion loss.
Nearly 90% of digital attacks begin with specifically targeted malicious emails.

To protect your company from the risks associated with email threats, you must secure your email servers.

This will minimize the chances of email security breaches and provide legal and regulatory compliance.

Minimizes Risks of Email Security Breaches

One of your business’s most significant risks is an email security breach. If this happens, it could lead to substantial financial losses for your company.

This is because hackers could steal sensitive information from your computer system or network and use it for their benefit.

Protection of Sensitive Data and Information

Email servers are the first defence against attacks on your company’s network and infrastructure. If a hacker gains access to an email server, they can use it as a conduit to the rest of your network.

This can result in data loss or theft and service interruptions that could seriously damage your reputation with customers.

Provides Business Continuity and Reputation Management

Suppose you don’t have adequate protection for your email servers. In that case, you risk losing sensitive data — from financial information to customer lists — which could lead to severe business disruptions or even bankruptcy if you’re not careful.

Protecting these systems is essential for maintaining business continuity and protecting your customer reputation.

Provides Legal and Regulatory Compliance

Companies must comply with various laws and regulations when managing their employee email accounts. For example, the European Union (EU) General Data Protection Regulation (GDPR) requires companies to have a Data Protection Officer who oversees compliance with GDPR requirements.

This includes securing employee data from unauthorized access or disclosure and ensuring employees understand their rights under GDPR legislation.

Expert-Recommended Best Practices for Ensuring Email Server Security

The first step in securing email servers is to use an email security gateway.

A good one will provide robust protection against known and unknown threats while keeping your organization compliant with regulatory requirements and best practices.

SPF Implementation

The SPF (Sender Policy Framework) protocol allows senders to specify which domains can send mail on their behalf. The SPF protocol uses TXT records in DNS records to determine the hosts that should be considered authorized to send emails from a particular domain.

For this verification system to work, both sender and receiver must support it.

DKIM Protocol

DomainKeys Identified Mail (DKIM) is another security mechanism that can help prevent spoofed emails from reaching your customers’ inboxes.

DKIM uses public-key cryptography and a digital signature to verify that an authorized source, such as your company, sent an email.

It also indicates that the message has remained the same since its creation. If a message fails either test, the receiving server will reject it as spam or junk mail and alert the recipient of its untrustworthiness.

DMARC Authentication

Domain-based Message Authentication Reporting and Conformance (DMARC) is an additional layer of security authentication that requires SPF and DKIM to confirm that an email was sent by the owner of the “friendly-from” domain that shows in the valid recipient’s DNS report. For this to happen, SPF and DKIM must be interwoven, and at least one must be aligned.

If SPF and DKIM pass, it confirms that the email came from a valid server and that the header information has not been altered.

The “From” domain and the “return path” domain must match the SPF to align. If DMARC fails, the recipient computer can either reject the email or move it to a folder other than the inbox, such as the spam folder.

DNSBL And RBL Implementation

DNSBL (DNS-Based Blackhole List) and RBL (Real-time Blackhole List) are spam-blocking lists that prevent spam emails from reaching your email server. DNSBL and RBL maintain known spam email sources and IP addresses databases.

An email from an IP address listed in the database will be blocked before it reaches the email server. Implementing DNSBL and RBL on your email server can significantly reduce the number of spam emails that your users receive. However, choosing reputable DNSBL and RBL providers is essential to ensure that legitimate emails are not blocked.

These features must be used to maintain the server free of spear phishing and spam emails.

Allow SURBL to validate message content

SURBL (Spam URI Real-time Block List) is a spam-blocking list that checks the URLs in the email message. The email will be blocked if the URL matches a known spam website. SURBL reviews the actual content of the email message rather than just the sender’s IP address. This makes it a more effective spam-blocking technique.

By allowing SURBL to validate message content, you can improve the accuracy of your spam-blocking and reduce the number of spam emails your users receive.

A SURBL filter shields users from malware and phishing assaults. Not all mail servers currently support SURBL.

But, if your messaging server enables it, activating it will boost the security of your server as well as the security of your entire network, as email content accounts for more than 50% of Internet security concerns.

Set Up Mail Transfer Agent (MTA) Strict Transport Security (MTA-STS)

You should configure your email server to support MTA-STS if your organization uses email. Strict Transport Security (MTA-STS) is a new protocol that allows email service providers (ESPs) to declare whether they support encryption for emails sent from their servers. Suppose your ESP supports TLS encryption for outbound mail. In that case, you can send messages to it securely by configuring your MTA to include a valid “strict-transport-security” entry in its DNS record.

Implement Domain Name System Security Extensions (DNSSEC)

DNSSEC is a security protocol that adds a layer of security to the DNS system. DNSSEC ensures that the DNS information received by your email server is authentic and has not been tampered with. Implementing DNSSEC on your email server can prevent DNS spoofing attacks, where an attacker modifies the DNS information to redirect users to a malicious website.

By ensuring the authenticity of the DNS information, DNSSEC can improve the security of your email server and protect your users from phishing and other attacks.

DNSSEC is critical to many other best practices, including enabling TLS on SMTP ports and using SPF/DMARC records.

Staying Ahead of Threats: Implementing Best Practices for Robust Email Server Security

Securing email servers is critical in protecting sensitive data and confidential communication from potential cyber-attacks. Email servers must be protected from external and internal threats to ensure email privacy, integrity, and availability.

Implementing best practices can significantly reduce the risk of email-related security breaches. Regular software updates and patches can also address any vulnerabilities that cybercriminals might exploit.

By staying ahead of threats and following best practices, businesses and organizations can ensure the security of their email servers and maintain the trust of their customers and stakeholders.

About
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Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

Best Practices for Securing Email Servers