Best practices for business email security

Email remains an essential communication tool in nearly every business operation, making it an indispensable, yet frequently targeted vector for cyber attacks. The pervasive use of email for internal discussions, client interactions, financial transactions, and sensitive data exchange makes it a prime target for malicious actors. Compromised email accounts or successful email-borne attacks can have severe and far-reaching consequences for an organization.

These risks extend beyond immediate financial losses, encompassing significant operational disruptions, legal and regulatory penalties, and irreparable damage to reputation and customer trust. A single successful phishing attempt, for example, can cascade into a complete network compromise, data exfiltration, or the deployment of ransomware, paralyzing business functions and demanding extensive recovery efforts. Robust email security measures are not merely an IT concern but a critical component of overall business resilience and risk management.

Organizations face various email security threats that exploit human behavior, technical vulnerabilities, or a combination of both. Understanding these attack vectors is essential for developing effective defense strategies.

Phishing

Phishing scams are a primary concern, involving deceptive emails designed to trick recipients into revealing sensitive information or performing actions that benefit the adversary. These scams often mimic legitimate senders, such as known companies, financial institutions, or even internal colleagues, to create a sense of urgency or authenticity. Variations include:

• Spear phishing: Highly targeted attacks directed at specific individuals or organizations, often leveraging publicly available information or prior reconnaissance to craft highly personalized and convincing lures.
• Whaling: A specialized form of spear phishing that targets high-profile individuals within an organization, such as executives (CEOs, CFOs), with the aim of manipulating them into authorizing fraudulent wire transfers or divulging sensitive corporate data.
• Business email compromise (BEC): Also known as CEO fraud, this sophisticated scam involves an adversary impersonating a high-ranking executive or a trusted business partner to trick an employee into transferring funds or sensitive information. BEC attacks often do not involve malicious links or attachments, making them difficult to detect with traditional technical controls.

Malware

Malware attacks delivered via email remain a significant threat. Adversaries embed malicious software within email attachments or link recipients to compromised websites that automatically download malware. Common malware types include:

• Ransomware: Encrypts an organization’s data, demanding a ransom payment for its release
• Spyware: Secretly monitors user activity and collects sensitive information
• Trojans: Disguise themselves as legitimate software but carry out malicious functions once executed
• Keyloggers: Record keystrokes to capture credentials and other sensitive input

Recipients may inadvertently trigger these attacks by opening seemingly innocuous attachments (e.g., invoices, resumes, shipping notifications) or by clicking embedded links that redirect to malware-hosting sites.

Spam

Spam often serves as a precursor or vehicle for more malicious attacks. While not always directly harmful, unsolicited bulk emails can contain phishing attempts, malware, or links to fraudulent websites. A high volume of spam can also reduce productivity and consume network resources. Effective spam filtering is therefore an important initial layer of defense.

Spoofing

Email spoofing involves forging email headers to make a message appear as though it originated from a legitimate source, when it did not. This technique is frequently used in phishing and BEC attacks to enhance credibility and to bypass basic security checks. Adversaries manipulate the “From” address to impersonate colleagues, vendors, or trusted entities, increasing the likelihood of a recipient trusting and interacting with the fraudulent email.

Employees are the primary users of email systems, and their actions directly influence an organization’s email security posture. While technological defenses are crucial, human behavior often represents the most significant vulnerability. A lack of awareness, adherence to poor security habits, or susceptibility to social engineering tactics can undermine even the most advanced technical controls. Therefore, fostering a strong security culture among employees is paramount for effective email protection.

Use strong passwords

A fundamental aspect of employee responsibility is the use of strong passwords. Weak, easily guessable, or reused passwords across multiple services create an open invitation for adversaries.

Best practices for passwords include:

• Length and complexity: Passwords should be long (e.g., 12-16 characters or more) and incorporate a mix of uppercase and lowercase letters, numbers, and symbols.
• Uniqueness: Employees must use distinct passwords for each business account to prevent credential stuffing attacks, where compromised credentials from one service are used to gain unauthorized access to others.
• Password managers: Encouraging or mandating the use of reputable password managers can help employees create, store, and manage strong, unique passwords securely.

Being cautious when opening emails from unknown senders or even suspicious emails from known senders is a critical defense mechanism. Employees should be trained to:

Verify sender identity

Always scrutinize the sender’s email address, looking for subtle misspellings or irregularities that indicate spoofing. For unexpected or highly sensitive requests, verify the sender’s identity through an alternative communication channel, such as a phone call to a known number, rather than replying to the email.

Inspect links

Before clicking, hover over embedded links to reveal the actual URL. Be wary of links that redirect to suspicious domains, even if the displayed text appears legitimate.

Exercise skepticism with attachments

Treat unexpected or unsolicited attachments with extreme caution, especially those with unusual file extensions (e.g., .exe, .zip, .js, .vbs) or from unfamiliar senders. If an attachment is suspicious, do not open it.

Recognize social engineering tactics

Employees should be educated on common social engineering lures, such as urgent requests, emotional appeals, threats, or enticing offers, which adversaries use to manipulate recipients.

Report suspicious activity

Establish clear procedures for employees to report suspicious emails or potential security incidents immediately. Timely reporting allows security teams to investigate, mitigate threats, and prevent widespread compromise.

Train your users

Regular security awareness training programs are essential to reinforce these behaviors. These programs should provide ongoing education on emerging threats, demonstrate real-world examples of attacks, and test employee vigilance through simulated phishing exercises. By empowering employees with knowledge and promoting a vigilant mindset, organizations can transform their human element from a potential weakness into a formidable line of defense against email-borne threats.

The proliferation of mobile devices and the shift towards remote work arrangements introduce additional complexities for business email security. While these environments offer flexibility, they also expand an organization’s attack surface. Implementing specific tips and guidance is essential to maintain robust email security regardless of location or device.

Securing mobile devices used for business email is paramount. This includes implementing:

• Device passcodes/biometrics: All devices accessing business email should be secured with strong passcodes, PINs, or biometric authentication (fingerprint, facial recognition). This prevents unauthorized access if a device is lost or stolen.
• Two-factor authentication (2FA): Also known as multi-factor authentication (MFA), 2FA adds an extra layer of security beyond a password. It requires users to provide a second form of verification, such as a code from a mobile authenticator app, a fingerprint scan, or a hardware token, before granting access to email. This significantly mitigates the risk of unauthorized access even if a password is compromised.
• Encryption: Device encryption, whether built into the operating system or enforced by policy, protects data stored on the device, including cached email content. If a device falls into the wrong hands, the encrypted data remains unreadable without the proper decryption key.
• Strong email service password: Even with 2FA, a strong, unique password for the email service itself remains a critical first line of defense.

When working remotely, the network environment often changes, necessitating additional precautions:

Use secure networks

Remote workers should avoid using unsecured public Wi-Fi networks for business activities, as these can be vulnerable to eavesdropping or man-in-the-middle attacks. If a public network must be used, a Virtual Private Network (VPN) should always be employed. A VPN encrypts internet traffic, creating a secure tunnel between the remote device and the corporate network. This protects email communications from interception and ensures data privacy when operating outside of the office.

Keep software updated

Regularly update the operating system, email client, and all applications on mobile devices and remote workstations. Software updates often include security patches that fix known vulnerabilities that attackers could exploit.

Utilize Mobile Device Management (MDM) solutions

MDM tools provide centralized control over mobile devices used for business purposes. MDM can enforce security policies, such as password complexity, encryption, remote wipe capabilities (in case of loss or theft), and app allowlisting, enhancing the overall security of mobile email access.

Beware of shoulder surfing

When working in public spaces, employees should be aware of their surroundings and prevent “shoulder surfing” where unauthorized individuals might view sensitive information on their screens.

These practices, when consistently applied, significantly strengthen the security of business email accessed from remote locations and mobile devices, contributing to a more secure overall operating environment.

Business email security is a critical pillar of an organization’s cybersecurity strategy, essential for safeguarding sensitive information and ensuring operational continuity. The pervasive use of email for nearly all business communications makes it an attractive target for cyber threats, which can result in significant financial, reputational, and operational damage. Common threats, such as sophisticated phishing scams (including spear phishing, whaling, and business email compromise), and malware attacks delivered through malicious attachments or links, continuously evolve to bypass traditional defenses.

Beyond technical measures, the human element plays a pivotal role in email security. Employees represent both a potential vulnerability and a crucial line of defense. Their vigilance in identifying suspicious emails, adherence to strong password practices, and prompt reporting of unusual activity are indispensable. Furthermore, securing email access in remote work environments and on mobile devices requires additional diligence, including the consistent use of device passcodes, two-factor authentication, data encryption, and secure network connections.

Ultimately, a comprehensive approach to email security integrates robust technological solutions with ongoing employee education and disciplined security practices. This layered defense helps organizations proactively mitigate risks, reduce their attack surface, and build resilience against persistent cyber threats.