Email is the lifeblood of modern business communication, but it also represents a significant security risk. Cybercriminals frequently exploit email vulnerabilities to gain access to sensitive data, deploy malware, and perpetrate fraud. Implementing robust email security measures is crucial for safeguarding your organisation’s data, reputation, and bottom line. A secure business email infrastructure is the foundation of effective email security.
By following these best practices and implementing robust security solutions, businesses can mitigate the risks associated with email-based threats and ensure the confidentiality, integrity, and availability of their email communications.
What can you do to protect your business email infrastructure? This guide will explore key business email security best practices to help organisations protect their email systems and data.
Table of Contents
1). Develop and Enforce a Secure Business Email Policy
The first step in securing your business email is to establish a comprehensive email policy that outlines acceptable use, security requirements, and incident response procedures. This policy should be regularly reviewed and updated to reflect evolving threats and best practices. It serves as a guiding document for employees, ensuring they understand their responsibilities and the consequences of non-compliance.
A well-crafted email policy should cover topics such as account management, password requirements, acceptable use of email for business purposes, and guidelines for handling sensitive information. It should also define roles and responsibilities for email security management and incident response. By developing and enforcing a clear and concise email policy, organisations can set the tone for a security-conscious email culture.
Separate email accounts for personal and business use
Separate email accounts for different purposes, such as personal and business use, can help reduce the risk of cross-contamination and minimise the impact of a potential breach. By maintaining distinct accounts, organisations can better control access to sensitive information, monitor activity, and limit the spread of threats. This practice also helps employees maintain a clear distinction between their professional and personal email communications, reducing the likelihood of inadvertent data leaks or misuse of company resources.
2). Train Employees in Email Security
Employees are often the weakest link in email security, as they can inadvertently fall victim to phishing attacks or engage in risky behaviour. Regular security awareness training is essential to educate employees on how to identify and respond to email-based threats. Employees should be trained to be cautious with links and attachments from unknown or suspicious sources, as these are common vectors for malware and phishing attacks. Training should cover topics such as recognising phishing attempts, verifying sender authenticity, handling sensitive information securely, and reporting suspicious emails. By empowering employees with knowledge and best practices, organisations can create a strong human firewall against email-based threats. Regular refresher training and simulated phishing exercises can help reinforce these lessons and keep employees vigilant in the face of evolving attack methods.
3). Secure Your Accounts
Implementing strong account security measures is crucial for preventing unauthorised access to your email accounts. Ensuring passwords are secure, enabling multi-factor authentication, keeping software up-to-date, and limiting email access are essential steps in hardening your email security posture.
Ensure passwords are secure
Using strong, unique passwords for each email account and avoiding password reuse across multiple accounts is a fundamental security practice. Passwords should be at least 16 characters long, include a mix of uppercase and lowercase letters, numbers, and special characters, and should not contain easily guessable information such as names, dates, or common phrases. Password managers can help generate and store complex passwords securely, reducing the burden on employees and improving overall account security.
Enable Multi-Factor Authentication
Multi-factor authentication (MFA) is one of the most effective ways to secure email accounts. It requires users to provide an additional form of authentication, such as a one-time code or biometric verification, in addition to their password. This extra layer of security significantly reduces the risk of unauthorised access, even if a password is compromised. MFA should be enabled for all email accounts, and organisations should consider implementing it across other critical systems and applications to create a consistent security framework.
Keep software up-to-date
Ensuring that your email client, operating system, and other software are kept up-to-date with the latest security patches and updates is crucial for maintaining a secure email infrastructure. Software vendors regularly release patches to address known vulnerabilities and security issues. By promptly applying these updates, organisations can close security gaps and reduce the attack surface for cybercriminals. Automating software updates or implementing a robust patch management process can help ensure that systems are consistently protected against the latest threats.
Limit email access to authorised devices and networks
Restricting email access to authorised devices and networks, and considering implementing remote access controls for added security, helps prevent unauthorised access and minimise the risk of data breaches. By limiting access to approved devices and networks, organisations can better control and monitor email activity, reducing the likelihood of data leaks or unauthorised access. Remote access controls, such as VPNs and secure remote desktop protocols, can help ensure that employees can access email securely from any location, while maintaining a high level of security and control.
4). Implement Strong Email Defences
Deploying robust email security solutions can help protect your organisation from a wide range of email-based threats, including spam, phishing, and malware. Secure email gateways, DMARC, SPF, content filtering, and incident response plans are essential components of a comprehensive email defence strategy.
Secure Email Gateway as a gatekeeper
A secure email gateway acts as a gatekeeper, scanning incoming and outgoing emails for threats and applying appropriate security policies. These solutions use advanced techniques such as machine learning and sandboxing to detect and block malicious content, while allowing legitimate emails to pass through. Secure email gateways can also enforce content policies, such as blocking sensitive information or enforcing encryption requirements, to ensure that email communications align with organisational security and compliance standards.
Implement DMARC and SPF
DMARC (Domain-based Message Authentication, Reporting & Conformance) and SPF (Sender Policy Framework) are email authentication protocols that help prevent email spoofing and phishing attacks by verifying the authenticity of the sender’s domain. DMARC allows domain owners to specify how their domain should be handled by receiving mail servers, while SPF defines which IP addresses are authorised to send email on behalf of a domain. By implementing DMARC and SPF, organisations can reduce the risk of their domain being used in phishing attacks and improve overall email deliverability.
Content filtering to detect and block emails containing malicious content
Content filtering solutions can detect and block emails containing malicious content, such as malware, phishing links, and inappropriate or sensitive information. These solutions use a combination of techniques, including signature-based detection, heuristics, and machine learning, to identify and quarantine suspicious emails. Content filtering can also help enforce data loss prevention (DLP) policies by identifying and blocking the transmission of sensitive information via email.
Develop and regularly test an Incident Response Plan
Developing and regularly testing an incident response plan is crucial for ensuring that your organisation is prepared to respond effectively to email-based security incidents. An incident response plan outlines the steps to be taken in the event of a security breach, including containment, eradication, and recovery measures. It also defines roles and responsibilities for incident response team members and establishes communication protocols for notifying stakeholders and regulatory authorities, if necessary. Regular testing and updates to the incident response plan help ensure that it remains effective and aligned with evolving threats and best practices.
5). Implement Email Encryption for Highly Sensitive Data
Email encryption is a critical security measure for protecting sensitive data in transit and ensuring the confidentiality of email communications. Email encryption ensures that only the intended recipients can read the contents of an email, even if it is intercepted during transmission. This is particularly important for businesses that handle sensitive or regulated data, such as financial information or personal data.
There are, however, different types of email encryption, each with their own benefits and trade-offs.
Gateway Encryption
Gateway encryption is an approach to email security that involves encrypting emails at the server level before they are sent to the recipient. This ensures that even if an email is intercepted during transmission, it remains encrypted and unreadable to unauthorised parties. Gateway encryption can be implemented using tools like Postfix or Exim, which support encryption protocols like TLS (Transport Layer Security).
Gateway encryption in Microsoft 365 can be implemented using Office 365 Message Encryption (OME), which is now officially called Microsoft Purview Message Encryption. This allows administrators to automatically encrypt emails based on policy rules, such as emails sent by members of specific groups or emails containing sensitive keywords or attachments.
Google Workspace does not currently offer a built-in gateway encryption solution comparable to Microsoft 365’s OME. However, there are some third-party solutions that provide gateway encryption for Google Workspace, including Virtru, Netskope, and Mimecast.
Client-Side Encryption
Client-side encryption is a different approach that encrypts data on the user’s device before it is sent to the cloud service provider. This ensures that even the service provider cannot access the unencrypted data.
Google recently expanded client-side encryption in Gmail to Android and iOS devices, allowing users to read and write encrypted emails directly from mobile devices. This feature is available to users with Workspace Enterprise Plus, Education Plus, or Education Standard accounts.
Microsoft 365 also supports client-side encryption through Double-Key Encryption (DKE) and Customer Key Encryption (also known as Bring Your Own Key or BYOK). These methods allow users to manage their own encryption keys, giving them full control over the encryption process.
However, client-side encryption in Microsoft 365 may have limitations and require specific licensing, such as the E5 family of licenses. Additionally, applying multiple email encryption technologies to the same email message can cause issues with some email clients.
End-to-End Encrypted Emails
End-to-end encryption ensures that only the intended recipients can read the contents of an email, even if it is intercepted during transmission. This is achieved by encrypting the email on the sender’s device and decrypting it only on the recipient’s device, with no intermediate decryption steps. End-to-end encryption helps protect against man-in-the-middle attacks and ensures that even if an email server is compromised, the contents of the email remain secure.
PGP (Pretty Good Privacy) and S/MIME (Secure/Multipurpose Internet Mail Extensions) are two widely used protocols for end-to-end email encryption. PGP uses public-key cryptography to encrypt and decrypt emails, while S/MIME is based on X.509 digital certificates. Both protocols provide a high level of security and are supported by many email clients and services.
As previously mention, while Microsoft 365 and Google Workspace provide advanced client-side encryption options (and may require specific licensing), they do not support built-in end-to-end encryption for all users by default.
For end-to-end encryption and businesses that require a higher level of security and compliance, email services like Proton Mail or Tutanota provide this feature by default. These services ensure that emails are encrypted on the sender’s device and decrypted only on the recipient’s device, without any intermediate decryption steps.
It is important to note that Proton Mail and Tutanota only encrypt emails by default when communicating within their own ecosystems, such as between two Proton Mail accounts or two Tutanota accounts. When sending emails to recipients using other email providers that do not natively support OpenPGP encryption/decryption and the Web Key Directory standard, additional measures are required to ensure encryption. In these scenarios, users must manually enable encryption, which typically involves sending the recipient a link to view the encrypted email after entering a password. This means that the recipient’s email provider, such as Gmail, can still access the unencrypted email contents, as the email is not end-to-end encrypted.
Key differences between end-to-end encryption, client-side encryption, and gateway encryption
- End-to-end encryption encrypts data on the sender’s device and can only be decrypted by the intended recipient’s device, with no intermediate decryption steps. The email service provider cannot access the decrypted emails.
- Client-side encryption also encrypts data on the user’s device before sending it to the email service provider. This ensures the provider cannot access the unencrypted data.
- Gateway encryption encrypts emails at the server level, either automatically based on policy rules or when the user sends the email. The email service provider can still access the decrypted emails.
- End-to-end encryption and client-side encryption protect emails both in transit and at rest on the server. Gateway encryption only protects during transmission, not necessarily at rest.
- While gateway encryption is implemented by the email service provider, end-to-end encryption and client-side encryption are implemented by the user on their own device.
The key difference is that with end-to-end encryption and client-side encryption, the email service provider cannot access the unencrypted emails. Gateway encryption provides less protection as the provider can still access the decrypted emails.
So in summary, end-to-end encryption and client-side encryption provide the strongest protection by ensuring emails remain encrypted and unreadable to email providers and third parties. Gateway encryption enhances security but has limitations compared to these user-controlled encryption methods.
GDPR Compliant End-to-End Encrypted Email Services:
For businesses that require a higher level of security and compliance, these GDPR-compliant, end-to-end encrypted email services can provide a secure and reliable solution for protecting sensitive data.
- Proton Mail: Proton Mail is a secure email service that offers end-to-end encryption, zero-access encryption, and is fully GDPR compliant. It is based in Switzerland and offers both free and paid plans.
- Tutanota: Tutanota is another GDPR-compliant, end-to-end encrypted email service that is based in Germany. It offers a user-friendly interface and a range of features, including calendar and address book integration.
Conclusion
Implementing robust business email security measures is essential for protecting your organisation from email-based threats and ensuring the confidentiality, integrity, and availability of your email communications. By following best practices, such as developing and enforcing a corporate email policy, training employees, securing accounts, implementing strong email defences, and utilising email encryption, businesses can significantly reduce their risk exposure and maintain a secure email infrastructure. Maintaining a secure business email environment requires ongoing vigilance, regular security assessments, and a commitment to continuous improvement. By staying informed about the latest threats and best practices, and adapting their security strategies accordingly, organisations can effectively safeguard their email communications and protect their valuable assets from cyber threats.
FAQ
Tips on How To Secure Business Emails Using Microsoft 365/Outlook
Microsoft 365 (formerly Office 365) offers a range of security features and tools to help secure business emails. Advanced Threat Protection (ATP) provides email filtering and malware protection, while Data Loss Prevention (DLP) helps identify and protect sensitive data. Encryption and information rights management (IRM) features allow users to secure email content, and multi-factor authentication (MFA) adds an extra layer of account security. To secure business emails using Microsoft 365/Outlook, organisations should enable ATP and DLP policies, configure encryption settings, and enforce MFA for all user accounts. Regular security audits and updates to these settings can help ensure that the email infrastructure remains secure and aligned with evolving threats and compliance requirements.
Tips on How To Secure Business Emails Using Gmail and Apple Mail
Gmail and Apple Mail also offer various security features and settings to help secure business emails. Two-factor authentication (2FA) provides added account security, while confidential mode in Gmail allows users to send encrypted and expiring emails. S/MIME encryption in Apple Mail helps secure email content, and advanced spam and malware filtering protect against common threats .To secure business emails using Gmail or Apple Mail, organisations should enable 2FA, configure confidential mode or S/MIME encryption, and ensure that spam and malware filtering settings are optimised for their specific needs. Regular security awareness training for employees can also help reinforce best practices for using these email clients securely.