Top 10 email security best practices

Email sits at the center of modern business communication and, unfortunately, at the center of most cyberattacks. The volume alone makes it irresistible to attackers: According to Barracuda’s 2025 Email Threats Report, one in four emails sent to businesses is malicious or unwanted spam. With that level of exposure, it’s no surprise that nearly 80% of data breaches involve phishing.

Those figures highlight a simple truth. Because email underpins nearly every critical process — approvals, contracts, payroll and credentials — its compromise can ripple across an organization, leading to financial losses, data exposure and operational downtime. Strengthening email protection best practices isn’t just about avoiding these outcomes; it’s about ensuring that daily communication remains trustworthy, efficient and resilient. 

This guide outlines how to secure email effectively by addressing the most common vulnerabilities and providing actionable, modern defense strategies.

Knowing how to secure email effectively starts with understanding what you’re up against. The email security threats below represent the most common and damaging tactics attackers use to exploit organizations of every size.

• Phishing & spear phishing: Deceptive emails impersonating trusted brands or colleagues to steal credentials or deliver remote-access tools. Often, the first step in ransomware attacks.
• Business email compromise (BEC): Socially engineered fraud where attackers impersonate executives or vendors to trick employees into sending money or sensitive data.
• Account takeover (ATO): Attackers use stolen credentials to access real corporate accounts, sending internal phishing emails or exfiltrating data undetected. 
• Data loss & insider threats: Employees accidentally or intentionally share sensitive information — through misdirected emails, attachments or personal forwarding.
• Spam & malware flooding: High volumes of junk email hide Trojans, phishing links or adware, creating alert fatigue and increasing risk of missed threats.
• Misconfigured security policies: Weak or missing settings (like unenforced DMARC or permissive allow-lists) open the door to spoofing and phishing.
• Lack of user awareness: Even the best defenses fail if employees can’t spot scams; human error drives the majority of email-related breaches.

The threats outlined above rely on the same weakness: a momentary lapse in visibility, verification or judgment. A modern, layered defense closes those gaps by combining technology, process and people.

The following 10 email protection best practices form the foundation of that approach, helping organizations not only block attacks but also build resilience when prevention fails.

1. Enable multifactor authentication (MFA)

If you implement only one measure from this list, make it MFA.  

Passwords can be stolen, guessed or leaked in third-party data breaches. MFA adds a mandatory second verification factor, such as a one-time code from an app, a push notification or a physical hardware token that stops most unauthorized logins cold. Microsoft reports that MFA blocks more than 99% of all account-compromise attempts. Enable it for all users, prioritizing administrators, executives and other privileged accounts. 

2. Enforce strong password policies and management

Weak, default or reused passwords remain a leading cause of data breaches. 

Establish a clear, enforceable policy that requires long, complex passwords (e.g., 12-16 characters minimum) and prohibits reuse across systems. More importantly, encourage or mandate the use of a password manager. These tools reduce friction for employees by generating and storing unique, complex credentials for every service, meaning users only have to remember one master password. Periodic password resets are less important than ensuring consistent credential hygiene from the start. 

3. Strengthen and standardize email encryption

Most organizations already use TLS to encrypt email in transit, but TLS only protects messages as they travel between mail servers. Once delivered or forwarded, those messages are often unprotected.

For sensitive or regulated content, add end-to-end email encryption (S/MIME or PGP) so only the intended recipient can decrypt it. Enforce encryption automatically for messages containing financial data, personal information or intellectual property. Beyond security, consistent encryption also supports compliance with frameworks such as HIPAA, GLBA and GDPR.

4. Deploy advanced email security solutions 

Modern threats are designed to outpace traditional spam filters. You need an advanced email protection platform, whether cloud-based or a secure email gateway, that uses AI and behavior analytics to detect attacks that signature-based filters can't identify.

Key capabilities to look for include:

• Attachment sandboxing: Executes all attachments in a safe, isolated virtual environment to detect malicious behavior (like reaching out to a command-and-control server or attempting to encrypt files) before the email is delivered to the user.
• Real-time URL protection: Scans links at the moment of click. This thwarts attackers who use dormant links that only "activate" with malware after the initial email has passed a security scan. 
• Phishing and impersonation detection: Uses machine-learning analysis of sender patterns, email headers and even language to catch BEC and spoofing attempts, even when no malware is present. It learns your organization's normal communication patterns and flags anomalies.

5. Conduct regular security awareness training

Ongoing training reinforces how to secure email systems at the human layer, turning your employees into a proactive line of defense rather than a point of failure. Regular, structured security-awareness training transforms your workforce from a target into a human firewall. This training must go beyond an annual slideshow; it should include brief, interactive sessions and simulated phishing exercises that test real-world reactions. 

6. Keep email systems and clients updated 

Visibility is at the heart of how to secure email across your organization. The earlier you detect anomalies, the faster you can contain them. Apply security patches and updates promptly across all mail servers (like Exchange), endpoints (Windows, macOS), email clients (Outlook), browsers, and mobile devices. Enable automatic updates wherever possible. Many of the most devastating breaches exploit vulnerabilities that already have fixes available. 

7. Use SPF, DKIM and DMARC

SPF, DKIM and DMARC are the backbone of domain authentication. These authentication protocols are a technical but vital defense against email spoofing and impersonation. They work together to prove that an email sender is who they claim to be.

Publish accurate SPF and DKIM records, then move beyond “monitor” mode in DMARC to full enforcement, rejecting messages that fail checks. Consistent enforcement stops most domain-spoofing and impersonation attacks before they ever reach an inbox. 

8. Monitor and audit email activity

You can’t respond to what you can’t see. Centralize your email logs and watch for anomalies, such as failed logins, unusual locations or sudden spikes in outbound mail that often signal a compromised account. Set automated alerts for stealthy moves like new forwarding rules to external addresses.

Feeding this telemetry into your Security Information and Event Management (SIEM) or security analytics platform adds critical context, helping you spot email threats early and connect them with other activity across your network.

9. Establish clear policies for handling sensitive information 

Define exactly what counts as sensitive data (PII, financial records, intellectual property) and spell out how it may be shared. Require encryption or secure file-transfer tools for anything confidential and make it policy that personal email is never used for company business.

Finally, bake in out-of-band verification: Any request for payments or sensitive data over email must be confirmed through another channel, like a phone call or chat.

10. Maintain an incident response (IR) and recovery plan

Everyone says, “It’s not if but when,” and for once, they’re right. But that doesn’t mean it has to be chaos when it happens. A practiced response plan turns panic into procedure. Define who does what, how incidents are escalated and how communication flows when email becomes the attack vector. 

• Contain: Disable compromised accounts, revoke sessions and isolate affected systems immediately to stop the spread.
• Eradicate: Trace how the attacker got in, remove malicious messages, revoke stolen credentials and patch exploited flaws.
• Recover: Restore clean data from verified backups and watch for signs of reinfection.

Following these email protection best practices helps build a layered, adaptable defense. When combined with technology and training, it’s the surest way to secure your inbox and your business.

For organizations seeking a consolidated, comprehensive approach, Barracuda Email Protection offers a powerful solution that combines gateway defense, AI-driven phishing and impersonation detection, automated remediation, data backup, and user-training tools in a single, integrated platform.

Key capabilities include:

• Spam, Malware and Advanced Threat Protection: Filters out spam, malware and advanced phishing attempts before they ever reach user inboxes. 
• Account Takeover Protection: Detects anomalous login behaviors and automatically quarantines compromised accounts.
• Incident Response: Automates incident response and provides remediation options to address issues faster and more efficiently.
• Security Awareness Training: Includes customizable phishing templates, gamified learning modules and built-in reporting tools that let users flag suspicious emails directly.

Ready to strengthen your organization’s posture? You’re welcome to evaluate the full platform with a free trial.