Email is the backbone of your business communication — and the #1 attack vector for cybercriminals. Phishing, business email compromise (BEC), and account takeovers all start with email, and small businesses are the most targeted because they typically have weaker defenses than large enterprises.
This guide covers the three biggest email threats and exactly how to protect against each one.
The 3 Biggest Email Threats
1. Phishing
Phishing emails impersonate trusted senders (your bank, a vendor, a colleague) to trick you into clicking malicious links, opening infected attachments, or entering credentials on fake login pages. Modern phishing emails are highly convincing — they use real logos, correct formatting, and urgent language.
Real-world example: An employee receives an email that appears to be from Microsoft saying their account will be deactivated. They click the link, enter their credentials on a fake Microsoft login page, and the attacker now has access to their email and everything connected to it.
2. Business Email Compromise (BEC)
BEC attacks target the money. An attacker either compromises a real email address or creates a lookalike domain, then sends emails requesting wire transfers, invoice payments, or changes to payment details. These emails are carefully researched and highly targeted.
Real-world example: An attacker spoofs your vendor's email domain (replacing "company.com" with "companny.com") and sends an invoice with updated bank wiring details. Your accounts payable team wires $45,000 to the attacker's account.
3. Account Takeover
Once an attacker has your email password (from phishing, a data breach, or credential stuffing), they can read your emails, send emails as you, reset passwords on other accounts, and access sensitive business data. They often set up email forwarding rules to monitor your communications silently.
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Set Up Email Authentication (SPF, DKIM, DMARC)
These three DNS records verify that emails from your domain are legitimate and help prevent attackers from spoofing your domain:
- SPF (Sender Policy Framework): Lists which servers are authorized to send email from your domain.
- DKIM (DomainKeys Identified Mail): Adds a digital signature to your emails that proves they haven't been tampered with.
- DMARC (Domain-based Message Authentication): Tells receiving servers what to do with emails that fail SPF or DKIM checks (reject or quarantine them).
Your email provider (Google Workspace, Microsoft 365) has guides for setting these up. It takes about 30 minutes and significantly reduces spoofing.
Use Email Filtering
Enable your email provider's built-in spam and phishing filters. Both Google Workspace and Microsoft 365 include basic protection. For businesses handling sensitive data, consider adding a dedicated email security layer like Webdefend Email Security, which catches sophisticated phishing that basic filters miss.
Train Your Team
Your employees are your last line of defense. Teach them to recognize these red flags:
Phishing Red Flags
- Urgent language ("Your account will be closed in 24 hours")
- Unexpected attachments, especially .zip, .exe, or .docm files
- Links that don't match the displayed URL (hover before clicking)
- Requests for passwords, credentials, or payment information
- Slight misspellings in the sender's email address
- Generic greetings ("Dear Customer" instead of your name)
- Requests to bypass normal procedures
How to Prevent Business Email Compromise
BEC attacks bypass technical filters because they don't contain malicious links or attachments — they're just convincing text. Prevention requires process changes:
- Verify payment changes by phone. Never act on an email request to change bank details or payment instructions without calling the sender using a known phone number (not one from the email).
- Require dual approval for wire transfers. No single employee should be able to initiate and approve a wire transfer.
- Watch for lookalike domains. Train your team to carefully check sender email addresses for subtle misspellings.
- Flag external emails. Configure your email system to add a banner to emails from outside your organization.
How to Prevent Account Takeovers
- Use unique, strong passwords. A password manager (like the one included with NordLayer Business) generates and stores unique passwords for every account.
- Enable MFA everywhere. If an attacker has your password, MFA stops them from logging in. Use an authenticator app, not SMS.
- Check for suspicious forwarding rules. Attackers often set up email forwarding to monitor your inbox. Check your email settings monthly for rules you didn't create.
- Monitor login activity. Both Google Workspace and Microsoft 365 let you review recent login activity. Look for logins from unfamiliar locations or devices.
Email Security Checklist
- SPF, DKIM, and DMARC records configured for your domain
- Email spam and phishing filters enabled
- Multi-factor authentication on all email accounts
- Unique, strong passwords (use a password manager)
- Team trained on phishing red flags
- Payment verification process in place (call before wiring)
- External email banners enabled
- Email forwarding rules reviewed monthly
- Login activity monitored for suspicious access
About Our Security Experts
The Small Business Security Guide editorial team is composed of independent cybersecurity analysts, risk assessment consultants, and technology writers. We focus exclusively on making enterprise-level security simple and accessible for small businesses. Our recommendations are entirely independent and based on rigorous, real-world testing of tools and security practices.
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Small Business Security Guide is fully independent. We evaluate security software over a 4-week testing protocol on dedicated business systems, measuring protection capability, system speed impact, setup complexity, and overall cost-per-device value. We may earn a commission if you sign up through our links, but commercial partnerships never influence our editorial scoring.
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Start Your Free TrialFrequently Asked Questions
Do I need email encryption for my small business?
If you handle sensitive customer information, financial data, or employee health information, yes - email encryption is likely required by law (HIPAA, GDPR, CCPA). Even without legal requirements, encryption protects against data interception and builds customer trust. Most business email providers (Google Workspace, Microsoft 365) offer encryption options. For sensitive communications, use encrypted email services or secure file transfer portals instead of regular email.
What's the difference between email security and spam filtering?
Spam filtering blocks unsolicited bulk emails. Email security includes spam filtering plus: phishing detection (identifying fake emails that impersonate trusted senders), malware scanning (blocking dangerous attachments), DMARC enforcement (preventing email spoofing), data loss prevention (preventing sensitive data leaks), and advanced threat protection. Business email security solutions like Microsoft Defender for Office 365, Mimecast, or Proofpoint provide comprehensive protection.
How does DMARC help with email security?
DMARC (Domain-based Message Authentication, Reporting & Conformance) tells email providers how to handle fake emails sent from your domain. When you set up DMARC with a 'quarantine' or 'reject' policy, spoofed emails are either blocked or sent to spam. This prevents attackers from impersonating your business in phishing emails. Monitor DMARC reports to see who's sending email from your domain and identify spoofing attempts.
Can I use Gmail or Outlook for business email security?
Both Google Workspace and Microsoft 365 include solid baseline email security. Google's Advanced Protection and Microsoft's Defender for Office 365 add advanced features. However, for high-value targets or regulated industries, consider dedicated email security providers like Mimecast, Proofpoint, or Barracuda that offer additional layers like sandboxing and advanced threat analytics. Evaluate based on your threat landscape and compliance needs.
What should I do if we receive a phishing email?
Report it immediately to your IT team or security provider. Don't click links, download attachments, or reply. Forward suspicious emails to your provider's abuse address (for Gmail: reportphishing@google.com). Document the incident for your security log. Run a quick scan on any devices that may have been exposed. If credentials were entered, change passwords immediately and enable MFA on all accounts. Consider sending a company-wide alert about the attempted attack.