Published 2025-04-10 by TechNet New England
Email remains the primary attack vector for cyber threats. Spam, phishing, malware, and business email compromise all arrive through your inbox. Robust email security is not optional. It is fundamental to protecting your business.
How Modern Email Security Works
Spam Filtering
The first line of defense blocks obvious junk:
- Reputation-based filtering checks sender history
- Content analysis looks for spam patterns
- Blacklists block known bad senders
- Machine learning improves accuracy over time
Anti-Phishing Protection
More sophisticated than basic spam filtering:
- URL scanning checks links for known malicious sites
- Time-of-click protection re-scans links when clicked
- Impersonation detection identifies spoofed senders
- AI analyzes writing patterns to detect anomalies
Malware Protection
- Attachment scanning for known malware signatures
- Sandboxing opens suspicious attachments in isolated environments
- Macro blocking prevents malicious Office macros
- File type filtering blocks dangerous extensions
Email Authentication
Technical standards that verify sender legitimacy:
- SPF: Specifies which servers can send mail for your domain
- DKIM: Adds a digital signature to verify message integrity
- DMARC: Tells recipients what to do with messages that fail SPF/DKIM
Microsoft 365 Email Security Options
For businesses using Microsoft 365:
- Exchange Online Protection (EOP): Basic protection included with all plans
- Microsoft Defender for Office 365: Advanced threat protection (Plan 1 or Plan 2)
- Third-party add-ons: Additional layers from specialized security vendors
Best Practices for Email Security
For Administrators
- Configure SPF, DKIM, and DMARC records
- Enable external email warnings to alert users
- Block auto-forwarding to external addresses
- Review and tune spam filter settings regularly
- Monitor security reports and quarantine
- Implement data loss prevention (DLP) policies
For Users
- Report suspicious emails rather than just deleting them
- Never click links in unexpected emails
- Verify unexpected requests through other channels
- Be cautious of urgency and emotional manipulation
- Use unique, strong passwords for email accounts
- Enable multi-factor authentication
Email Security Red Flags
- No SPF, DKIM, or DMARC records configured
- Users regularly receiving obvious spam
- No process for reporting suspicious emails
- No external email banners or warnings
- MFA not enabled on email accounts
- Email auto-forwarding allowed to external addresses
Email security requires multiple layers: technology, configuration, and user awareness working together. Contact TechNet New England for an email security assessment.