Understanding Email Spoofing and How to Prevent It
Ransomware and other forms of cybercrime often make headlines, but one type of cyberattack, email spoofing, receives little attention despite posing significant security risks. Spoofed emails in business email compromise attacks alone resulted in $2.9 billion in losses in 2023.
Email spoofing attacks don’t just target large enterprises. SMBs are also susceptible to attackers who impersonate executives, vendors, and other trusted senders to manipulate email recipients into transferring money or sharing sensitive business information.
For example, a small accounting firm may receive what appears to be an email from a long-term client requesting an urgent wire transfer, or a local construction company might get an “invoice correction” email from a supplier they work with every week.
What Is Email Spoofing?
Email spoofing is a type of cyberattack in which an imposter sends a deceptive email that appears to come from a trusted or legitimate source.
Everyone is familiar with the From, To, Subject, and Date fields that appear at the top of email messages. A hidden section of software code known as an email header generates those fields. An email header contains detailed information about the sender, the recipient, and the message’s routing. In spoofing attempts, attackers manipulate the email header information to disguise their true identities.
The primary goal of email spoofing is to earn a recipient’s trust. Cybercriminals use this technique to gain access to IT networks to carry out phishing attacks, business email compromise schemes, and other forms of cyber fraud.
A common real-world example is when an employee receives an email that looks like it came from Microsoft 365 support asking them to “verify their account immediately.” The email may look professional, include logos, and even use language similar to legitimate IT notifications.
By masquerading as a colleague, company executive, or reputable business, attackers try to trick email recipients into taking actions or revealing sensitive information that they otherwise wouldn’t, such as clicking on harmful links, downloading malware, or revealing corporate login credentials.
Some attackers also use email spoofing to damage a company’s reputation. For instance, criminals may spoof a business’s email domain to send spam or scams to customers, making it appear that the company itself is untrustworthy.
How Does Email Spoofing Happen?
Email spoofing targets businesses by exploiting a fundamental weakness in how email works. When someone receives an email, the From field isn’t automatically verified. A scammer can easily falsify the From address, similar to writing a fake return address on a physical letter.
Attackers use this vulnerability to impersonate trusted email senders.
For example, an attacker might send an email that appears to come from your HR department with the subject line:
“Updated Direct Deposit Form Required Immediately”
An employee may open the attachment without realizing it contains malware or is part of a credential-stealing scheme.
Attacks against businesses generally use two different methods of deception to make it appear that the email came from a trusted source:
- Domain spoofing
If your business’s domain email authentication protocols haven’t been properly configured, attackers can send emails that appear to be from your domain. Mail servers receiving the messages will recognize your domain as genuine and won’t reject them.
For instance, an attacker could send an email appearing to come from:
finance@yourcompany.com
…asking a vendor to send future payments to a “new account.”
- Look-alike domains
An attacker can register a domain that looks similar to your business. For example, mybusness.com rather than mybusiness.com and send a malicious email incorporating the fake domain’s address name to deceive a recipient.
A real-life example is replacing letters that look similar, such as:
- rn instead of m
- 0 instead of o
- .co instead of .com
Employees often don’t notice these subtle differences when reading quickly on a phone screen.
Examples of Email Spoofing
Attackers use these methods to impersonate employees, company executives, clients, customers, or vendors. Once a recipient believes that the sender looks legitimate, an attacker uses social engineering tactics in the email text to evade your team’s defenses.
Common examples of email spoofing include:
- An employee receives an email from a “colleague” asking for sensitive business information or corporate login credentials.
Example: A fake IT email requests the employee’s password to “fix an urgent mailbox issue.”
- An assistant receives an email from the “CEO” asking him to buy dozens of gift cards to send out as employee rewards. The CEO asks the assistant for the cards’ serial numbers so she can email them to employees immediately.
This scam is extremely common around holidays, when businesses are already sending bonuses and gifts.
- A known “vendor” sends an email with an invoice attached, which has an “updated” bank account number to receive the funds via an electronic fund transfer.
For example, a manufacturer might unknowingly send a $40,000 payment to a criminal’s account instead of their supplier’s.
- A customer receives a spoofed email pretending to be from your business confirming a fake order or delivery, prompting them to click a malicious tracking link.
Because these messages appear to come from trusted sources, employees may comply with requests without questioning the emails’ authenticity.
For SMBs, a single successful spoof can result in significant data breaches, financial losses, or reputational harm.
How to Respond to an Email Spoofing Attack
When you learn that an employee has received a spoofed email, immediately alert your team through a verified communication channel. Reset passwords for compromised accounts and strengthen user authentication protocols across all systems.
If the spoofing involves a financial request, immediately contact your bank to freeze accounts or recall a fraudulent transfer.
For example, businesses that report wire fraud within the first few hours have a much better chance of recovering funds than those that discover it days later.
Collect all available information about the spoofed emails, including complete headers showing authentication failures and originating IP addresses. Document when your team first detected the spoofing attack and any patterns in its targeting or content. This evidence will benefit your internal investigation, help law enforcement, and be valuable in any lawsuit.
If your business email domain has been spoofed, your company may not be legally liable for the scam itself. However, you have an ethical duty to notify potentially affected parties and to protect your business’s reputation.
If a criminal spoofs your domain to deceive email recipients, notify all affected external stakeholders directly, particularly customers, partners, and vendors. Also, consider posting prominent warnings on your website and social media to alert potential unknown victims. Immediately report the incident to law enforcement and your email service provider. Consider hiring a cybersecurity professional to help your IT team assess vulnerabilities.
Taking swift action helps preserve your brand’s reputation and mitigates financial loss.
What You Can Do to Prevent Email Spoofing
SMBs can strengthen their defenses against email spoofing attacks by taking these key steps:
1. Implement email authentication protocols
Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication (DMARC) records in your Domain Name System (DNS) settings. These authentication standards help external email servers verify that emails claiming to be from your domain are legitimate.
2. Use strong passwords and robust authentication
Adopt mandatory companywide password rules and protect email accounts with multi-factor authentication to prevent account takeovers that enable spoofing.
3. Use email security software
Email security solutions can detect, and block spoofed messages before they reach staff inboxes.
4. Train employees
Regular security awareness training significantly reduces the success rate of spoofing attacks. Educate staff to recognize email spoofing red flags, such as:
- Slight variations in domain names
- Urgent financial requests
- Unexpected attachments
- Messages with odd tones or grammar
For example, if an email from the “CEO” suddenly uses informal language or demands secrecy, that’s a major warning sign.
Employees should use trusted contact channels to confirm any requests for sensitive business information, immediate action, financial transfers, or credential changes.
5. Monitor your domain
Regularly check for unauthorized use of your brand in emails. Register similar domain names to lower the risk of look-alike domains.
For example, many businesses register common misspellings of their domain to prevent attackers from using them.
Spoof-proof Your Business
The financial and reputational costs of falling victim to an email spoofing attack far exceed the cost of prevention. By adopting email and domain best practices and training your staff to spot spoof attempts, you can protect your bottom line and preserve the trust of your customers and business partners.
If you have concerns about your business’s vulnerability to email spoofing or other cyberattacks, contact us today to speak to an IT security expert or to request a free network security assessment.
About the Author: Jordan Ehrman
