Email has become an indispensable communication tool in business and personal life. However, the prevalence of email also makes it a prime target for cybercriminals looking to steal sensitive information or spread malware. Fortunately, there are a variety of robust email security solutions available to help protect organizations and individuals.
Why is email security important?
There are several key reasons why implementing email security measures is critical:
- Email phishing attacks – Phishing emails aim to trick users into providing login credentials or other sensitive information by mimicking trusted sources. They are a leading cause of data breaches and identity theft.
- Malware distribution – Email is often used to spread malicious software like viruses, worms, and spyware. These can lead to compromised systems, data theft, and network damage.
- Email spoofing – Spoofing occurs when the sender address is altered to impersonate someone else, usually to appear more legitimate. This facilitates phishing and social engineering schemes.
- Spam – While mostly a nuisance, excessive spam still reduces productivity and strains IT resources due to the scale of unwanted messages.
- Regulatory requirements – Industries like healthcare and finance have stringent data security regulations that include provisions for email security.
Robust email security provides multiple layers of protection against these and other threats. This minimizes an organization’s attack surface and safeguards sensitive systems and data.
Types of email security tools
There are a wide array of solutions available to bolster email security postures. Major tool categories include:
Email gateways
Email gateways, also called email proxies, are placed at the edge of the network where inbound and outbound email is inspected. They provide:
- Spam filtering
- Malware scanning via signature databases and machine learning
- Policy enforcement for acceptable attachments and content
- Protection against phishing attempts and impersonation
- Email encryption capabilities
Leading vendors include Mimecast, Proofpoint, Barracuda, and Microsoft.
Endpoint email clients
Endpoint email clients like Microsoft Outlook also incorporate security measures like:
- Junk email recognition
- Sender authentication checks
- WARNINGS against risky links and attachments
Extra features may include sandboxing attachments in isolated environments before delivery to users. This helps catch malware missed by other layers.
DNS-based security
DNS filtering solutions can identify and block emails from malicious domains associated with malware, phishing, and spam campaigns. This prevents connections before emails even reach the network perimeter.
Securing webmail
Since many employees utilize web-based email services, like Gmail and Office 365, securing webmail should also be part of an organization’s strategy. Solutions like cloud access security brokers (CASBs) apply policies and protections to webmail traffic.
Data loss prevention
Data loss prevention (DLP) tools scan outbound email for sensitive data like PII or financials to prevent accidental or malicious leaks. DLP can block, encrypt, or flag emails based on policy. It’s an important data protection measure for many compliance frameworks.
User education
With email threats constantly evolving, training staff to recognize warning signs is critical. Well-informed users provide an additional layer of protection to technical controls. Education helps avoid falling victim to new or clever social engineering tactics.
Key email security measures
Every organization should consider implementing these core email security best practices:
Multifactor authentication
Require an additional step like a code from an authenticator app to login to email accounts. This prevents unauthorized access even if credentials are compromised.
Encryption
Encrypting email in transit and at rest safeguards messages from potential interception or data leaks. S/MIME and TLS are common protocols.
Strong password policies
Enforce password complexity, regular rotation, and lockouts to prevent brute force attacks and abuse of weak passwords. Ban common and reused passwords.
Sender Policy Framework (SPF)
SPF confirms legitimate sending hosts to stop domain spoofing. Receiving servers validate senders against published SPF records.
DMARC
Domain-based Message Authentication, Reporting & Conformance (DMARC) builds on SPF and DKIM email authentication. It provides visibility into misuse of domains and prevents spoofing.
Mail transfer agent (MTA) rules
Configure the MTA with rules to filter out suspicious senders, subject lines, attachments, and content indicative of spam and malware campaigns.
Allowlists
Only allow email from certain trusted domains and senders. All other messages are blocked by default.
Regular patching and updates
Routinely patch and update email platforms, clients, and mail gateways to address vulnerabilities as they are discovered.
Backups
Maintain regular backups of email data to quickly restore service in the event of an outage or damage from an attack.
Incident response plan
Have an IR plan in place for email security incidents like data breaches, malware introduction, or service disruption.
Choosing an email security solution
With many products available, focus on these criteria when selecting an email security solution:
Breadth of protection
Look for a comprehensive suite of threat prevention and compliance capabilities spanning phishing, impersonation, malware, spam, DLP, and authentication.
Flexible deployment
Support for cloud, on-premises, and hybrid installations based on an organization’s infrastructure strategy and needs.
Ease of use
Intuitive interfaces and workflows for administrators and end users to ensure adoption across the organization.
Scalability
The solution must easily scale to handle growth in mail volume and users without compromising performance or availability.
Interoperability
Seamless integration with existing email environments, directory services, endpoint clients, and productivity suites.
Reporting
Robust default reports on security trends, threats detected, policy violations, and more to meet compliance needs.
Support and maintenance
Timely updates and patches, reliable support resources, training options, and maintenance renewals.
Cost
Total cost of ownership including licenses, maintenance, training, customizations, and infrastructure requirements.
Implementing a secure email gateway
Deploying a dedicated email security gateway is one of the most effective measures an organization can take. The major steps include:
- Select a solution that meets your organization’s requirements after thorough evaluation.
- Purchase appropriate licenses and appliances based on mail volume and redundancy needs.
- Integrate the gateway with your mail servers and directory services for authentication.
- Import existing allowlists, blocklists, and other policies to enforce.
- Configure default security policies for spam, malware, phishing, DLP, authentication, encryption etc.
- Route all inbound and outbound email through the gateway.
- Fine-tune policies and monitor performance during a testing period before full production rollout.
- Provide user awareness training on the technology and embedding safe email habits.
- Regularly review reports and metrics to ensure maximum effectiveness.
- Keep policies current by updating content filters, allowlists, and rules to adapt to the threat landscape.
Plan for this implementation to take from two weeks to two months depending on environment complexity. Some platforms also allow for a gradual phase-in to different user groups.
Securing Microsoft Office 365 email
As one of the most widely adopted cloud email services, it’s important for organizations using Office 365 to enhance its native security. Recommended actions include:
- Enable multi-factor authentication for administrator accounts and regular users.
- Restrict Office 365 email access to VPN or zero trust network to limit exposure.
- Route Office 365 mail through a cloud email gateway for an added layer of protection.
- Adjust junk mail filtering aggressiveness and customize blocked sender lists.
- Remove previous employees’ email accounts and distribution groups.
- Leverage the Office 365 Advanced Threat Protection (ATP) module for enhanced malware and phishing detection.
- Ban external email forwarding to prevent data exfiltration.
- Enable Office 365 auditing and alerts to identify suspicious activity.
- Frequently check the Office 365 Secure Score to identify areas for improvement.
- Provide Office 365 security training to employees to aid in identification of business email compromise attacks.
Third-party tools also exist that provide more robust Office 365 security settings management, compliance capabilities, and threat protection.
Email security best practices for small businesses
Small businesses face many of the same email threats as larger enterprises, but often lack comparable resources. A few key steps small business should take include:
- Use a commercial email suite like Office 365 or G Suite over consumer-grade options. These include more security capabilities.
- Add an extra dedicated spam filtering service if the provider’s built-in tools are inadequate.
- Enable multi-factor authentication for all employee accounts to prevent password breaches.
- Create a separate shared mailbox for general inquiries instead of using a salesperson’s email.
- Educate staff on how to identify and handle suspicious emails to reinforce human firewalls.
- Back up email data regularly to aid recovery if accounts are compromised.
- Consider outsourcing email security management and monitoring to an MSSP if in-house skills are insufficient.
The National Cyber Security Alliance’s “Small Business Email Security Guide” also provides a wealth of tips to better protect company and customer data.
Email security awareness training
Technical controls are only part of an effective email security program. Employees also need continuous training to recognize and handle suspicious messages properly. Training should cover topics like:
- Identifying spam, phishing attempts, and social engineering techniques
- Handling email threats and reporting suspicious messages
- Dangers of email attachments and unsafe links
- Secure email practices like using digital signatures and encryption
- Policies for email data and acceptable use
- How to recognize business email compromise scams
- Consequences of risk behaviors like email account compromise
Frequent simulated phishing attacks should also be conducted to reinforce skills and identify areas for improvement. Maximizing human defenses through education is imperative for email security.
Email security monitoring best practices
Ongoing monitoring of email security controls and solution effectiveness provides visibility into any gaps requiring remediation. Key monitoring actions include:
- Review email gateway reports regularly for trends related to spam, malware, blocked attacks, policy violations etc.
- Monitor gateway uptime and performance to ensure availability.
- Check administrator and user mailboxes for anomalies indicative of a security breach.
- Confirm allowlists/blocklists are updated based on latest intelligence.
- Verify security policies and filters are current and adjusted based on new techniques.
- Check progress on email security awareness training efforts and phishing simulation results.
- Confirm employees are adhering to sound email security practices.
- Review logs and reports following any email-based incident to identify deficiencies.
Proper metrics should also be defined based on risk appetite. Trigger thresholds that indicate a critical issue requiring immediate response.
Email security for remote workers
With remote and hybrid work environments now common, extra effort is required to secure employee email outside the corporate perimeter. Key considerations include:
- Implementing multi-factor authentication for remote access to email.
- Blocking email forwarding rules to external domains.
- Restricting remote email access to managed devices with endpoint security controls.
- Steering employees towards webmail and mobile apps over local email clients.
- Enforcing timeout requiring reauthentication after periods of inactivity.
- Ensuring VPN or zero trust network protection for all remote email access.
- Preventing copies of email data on remote devices through data loss prevention controls.
- Including remote workers in email security awareness training and simulations.
It’s also wise to assume any personal devices used for remote email access are already compromised from a security standpoint.
Email security regulations and compliance
In regulated industries like healthcare and finance, organizations must adhere to strict email security and retention requirements. Some of the major compliance frameworks include:
HIPAA
The Health Insurance Portability and Accountability Act (HIPAA) governs protected health information (PHI). It requires covered entities to implement email security controls like:
- Encryption of PHI in emails
- Secure transmission of email between servers
- Limiting PHI access only to authorized personnel
- Detailed auditing of PHI-related emails
FINRA
Financial Industry Regulatory Authority (FINRA) regulations impose cybersecurity requirements on financial firms including:
- SEC Rule 17-a4(f) mandating email archiving for at least three years
- Encryption of confidential information like financial account details
- Multi-factor authentication for webmail access
- Protections against phishing attacks
PCI DSS
The Payment Card Industry (PCI) Data Security Standard (DSS) applies to any entity handling payment card data. It stipulates measures like:
- Prohibiting transmission of unprotected PANs via email
- DMARC implementation to combat email spoofing
- Prompt removal of ex-employees’ email access
- Two-factor authentication for webmail administrative access
GDPR
The European Union’s General Data Protection Regulation (GDPR) governs email communications containing EU citizen personal data, requiring:
- Consent for collecting and transferring email data
- Encryption and PII scrubbing from email databases
- Data breach notifications within 72 hours
- Secure transmission and storage of emails
Conclusion
Email represents one of the top digital attack vectors threatening organizations today. Implementing a robust, layered email security platform with user training is essential to counter sophisticated phishing, malware, impersonation, and data exfiltration tactics. Monitoring solution effectiveness and adjusting defenses continuously are also key to mitigate this dynamic threat.
With digital communication central to business, establishing enterprise-grade email security safeguards provides assurance against debilitating breaches or outages. The business value delivered by securing this vital communication artery more than justifies the investment.