Inside the Inbox: How Email Really Works and How to Stop Hackers in Their Tracks

In today’s digital-first world, your email system is much more than just a way to send messages. It's a lifeline connecting you to clients, vendors, partners, and team members. Because of this, it's also a prime target for cyber criminals. If you’re a business leader or owner of a small to medium-sized business (SMB), understanding how email delivery works and how to harden it against attack is critical. In this Knowledge Base release, we'll walk through how email travels and then translate those steps into practical security actions that you must take today.

The Journey of an Email

Let’s trace the path of an email, step by step, from creation to delivery and uncover where security matters most. Here's what the sequence typically looks like (your exact workflow may slightly vary):

• You compose your message in an email client such as Gmail, Outlook, or any other mail application.

• Your client connects to an outgoing mail server using the SMTP protocol (Simple Mail Transfer Protocol). Common ports for secure delivery are 465 or 587 (port 25 is often blocked or restricted due to abuse).

• That SMTP server checks the recipient domain, determines how to route the message, and may relay it through additional servers if needed.

• Once the message reaches the recipient’s mail server, it may be stored or queued (via IMAP or POP3 protocols, or modern equivalents) until the recipient retrieves it.

• The recipient opens their mail client or webmail application and views the message: mission accomplished.

  
  

While that may seem relatively straightforward, each stage of this process introduces serious vulnerabilities for your business.

Some sobering statistics:

• Small businesses receive malicious emails at the rate of approximately 1 in 323 messages for organizations under 250 employees. StrongDM

• Employees at small businesses experience 350 % more social-engineering attacks than those at larger enterprises. StrongDM

• According to one study, 94 % of organizations have reported an email security incident. PreVeil

  
  

In short: email is one of the most common doors through which attackers enter. How ready is your business to defend that door?

Key Security Protocols You Should Know

When securing your email infrastructure there are several key protocols and practices that you must implement and enforce:

• SPF (Sender Policy Framework): A DNS record that authorizes which mail servers may send on behalf of your domain.

• DKIM (DomainKeys Identified Mail): Adds a digital signature to your outgoing mail, which recipients can verify.

• DMARC (Domain-based Message Authentication Reporting & Conformance): A policy layer that tells recipient mail servers how to handle messages that fail SPF or DKIM and lets you receive reports about failed attempts.

• TLS (Transport Layer Security): Ensures that the mail transfer between servers is encrypted, preventing passive eavesdropping or content tampering.

• MFA (Multi-Factor Authentication): Ensures that, even if credentials are compromised, unauthorized logins become much more difficult.

• User training & awareness: Since humans are consistently the weakest link, training your team to recognize phishing, check sender identity, verify unexpected requests, and hover over links before clicking is essential.

Practical Guidance for SMBs

Here's your step-by-step checklist to tighten email security:

1. Verify your DNS records for SPF, DKIM and DMARC

   • Make sure your domain has an SPF record specifying your authorized sending servers.

   • Enable DKIM signing on your outbound mail servers so recipients can verify the signature.

   • Publish a DMARC policy with at least “none” initially (monitoring mode) and review the reports. Gradually move to “quarantine” or “reject” as your infrastructure proves reliable.

   • Review DMARC failure reports monthly to spot unauthorized senders or spoofing attempts.

2. Enforce secure submission and encryption

   • Ensure your email clients and servers use ports 465 or 587 with TLS, and discourage use of insecure port 25 for submission.

   • Ensure your mail servers enforce TLS negotiation for both inbound and outbound mail whenever possible.

3. Require multi-factor authentication for all business email accounts

   • No exceptions. Even if an employee’s password is compromised, MFA provides a strong second barrier.

   • Maintain a process for securely revoking credentials when staff leave or roles change.

4. Train your team on phishing, spoofing and social-engineering risks

   • Conduct regular phishing-simulation campaigns to test and improve awareness.

   • Teach staff to pause before responding to financial requests, fund transfers, or unexpected attachments.

   • Encourage verification of sending addresses, especially when requests appear to come from executives or vendors.

5. Establish an incident-response plan

   • Identify who to contact internally and externally (e.g., IT provider, cybersecurity vendor, your bank) if you suspect a compromise.

   • Define a process for isolating compromised accounts, resetting credentials, analyzing logs, and documenting actions.

   • Back up your email archive and data regularly so you can recover quickly from any incident.

6. Review vendor and third-party email risks

   • If you rely on external services (e.g., outsourced IT, cloud-based mail platforms, partners that send email on your behalf), make sure they also enforce SPF, DKIM, DMARC and MFA.

   • Require vendors to share evidence of their email security controls.

Why Prioritize This Now

For an SMB, the cost of neglecting email security can be severe: financial loss, reputational damage, regulatory penalties and, in some cases, business closure.

If your business treats email as just “business as usual” without dedicated controls, you're inviting risk... But if you treat it as a critical asset and protect it accordingly, you'll dramatically boost your resilience.

Final Thoughts

Email obviously delivers huge value to your organization, enabling communication, coordination and customer engagement. But it also introduces one of your biggest attack surfaces. By implementing the protocols and controls above, you not only secure that surface, but you also demonstrate to customers, partners, and regulators that your business takes data protection seriously.

Ask yourself (and your leadership team):

How confident are you that your business’ email security is truly locked down?

If you hesitated at all... now is the moment to act.

If you’d like help reviewing your email infrastructure or want a guided audit of SPF, DKIM, DMARC and training for your team, we’re here to assist.

Just reach out and we’ll help you to build a rock-solid email defense.