How can I prevent brand and sender profile impersonation in emails and what actions can I take?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Jul 2025
Updated 16 Aug 2025
8 min read
Email impersonation is a pervasive and challenging threat that extends beyond simple domain spoofing. While traditional email authentication protocols like DMARC are highly effective against direct domain impersonation, attackers often use more subtle tactics. They might leverage your brand name, display name, or even a reply-to email address to trick recipients, making it appear as though the email originates from a trusted source, even when the underlying domain is different. This can lead to significant damage to your brand's reputation and trust with your customers.
The challenge intensifies when impersonators don't even use a lookalike domain, but instead rely purely on your brand's visual identity or common sender names to deceive. This is often the case in Business Email Compromise (BEC) attacks, where criminals impersonate executives or vendors. Protecting against this requires a multi-faceted approach, combining robust technical measures with proactive monitoring and widespread user education.
It’s important to distinguish between different forms of email impersonation. Domain spoofing, where an attacker sends an email from your exact domain without authorization, is typically what DMARC, SPF, and DKIM are designed to combat. These protocols verify that an email truly originates from your domain. You can learn more about what to do if your domain gets spoofed in our guides.
However, a brand impersonation often involves using a familiar sender name (like 'CEO' or 'Support Team') and a reply-to address that looks legitimate, even if the actual sending domain is a free email service or a completely unrelated one. Since the 'Reply-To' header is not protected by standard email authentication, it’s a common vector for attackers to exploit. This type of attack is designed to bypass some of the more technical email filters that rely on domain verification.
The goal is to confuse the recipient into believing the email is authentic. Your users may receive emails that visually match your branding, using your logos and content layout, but originate from an entirely different, malicious source. This makes it difficult for recipients to discern the legitimacy of the message, leading to potential data breaches, financial fraud, and a significant erosion of trust in your communications.
Technical defenses against impersonation
The first line of defense against both domain spoofing and many forms of impersonation lies in implementing strong email authentication. Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) are fundamental. DMARC, in particular, allows you to tell receiving mail servers what to do with emails that fail authentication (e.g., quarantine or reject them), providing a robust defense against unauthorized use of your domain. A simple guide to DMARC, SPF, and DKIM can help you get started.
To achieve maximum protection, aim for a DMARC policy of 'p=reject'. This instructs recipient servers to reject any email purporting to be from your domain if it fails DMARC authentication checks. While this is the strongest policy, it requires careful implementation to avoid legitimate emails being blocked. Begin with 'p=none' to gather reports and move to 'p=quarantine' before progressing to 'p=reject'. Here’s how to safely transition your DMARC policy.
Brand Indicators for Message Identification (BIMI) can also play a role, although it doesn't prevent impersonation directly. BIMI allows your brand's logo to appear next to your email in supporting inboxes. While it doesn't authenticate the sender, it offers a visual cue of legitimacy. If your domain is DMARC-protected at a 'quarantine' or 'reject' policy, a legitimate email will display your logo, making it easier for users to spot emails that lack it as potentially fraudulent. Learn more about the business value of BIMI.
Sample DMARC record (p=reject)
This DMARC record instructs recipient servers to reject emails that fail authentication and send aggregate reports to dmarc@example.com. It’s a powerful step towards preventing unauthorized use of your domain.
Even with robust authentication in place, proactive monitoring is essential. You need to keep an eye on how your brand is being used across the internet, not just within email. This includes monitoring for lookalike domains, fake social media profiles, and other instances of brand abuse. Implement a system to continuously monitor your digital footprint for suspicious activity. If you're looking for unauthorized brand use in email marketing, we have a guide on tools and methods to monitor unauthorized brand use.
When users report suspicious emails, it’s critical to gather as much information as possible. This typically means asking for the full email headers, which contain vital routing information that can help trace the origin of the message. If your support team doesn't regularly collect headers, consider setting up a dedicated 'abuse@' mailbox or training a specific person to handle these inquiries. It's the only way to get a full picture of the attack.
With the headers, you can identify the actual sending IP address and often the email service provider. This information allows you to pursue legal action if necessary, or report the abuse to the relevant service provider, who can then take steps to shut down the malicious sender. You can also use services like wheregoes.com to trace redirect URLs within suspicious emails.
Additionally, proactively setting up spam traps can help. These are dormant email addresses specifically designed to catch spam and fraudulent emails. When an impersonation email lands in a spam trap, it provides valuable intelligence about the tactics and sources of the attackers. This information can then be used to strengthen your defenses and inform blocklist (or blacklist) operators.
Information to gather
Why it's important
Full email headers
Reveal sender IP, authentication results, and email routing path, crucial for identifying origin.
Different clients display headers differently and might offer varied reporting options.
Educating your organization and users
Beyond technical safeguards, employee and customer education forms a critical layer of defense. Many impersonation attacks succeed because recipients don't know what to look for. Train your internal teams to recognize phishing attempts, especially those that impersonate internal executives or trusted partners. This includes scrutinizing sender names, checking the actual email address (not just the display name), and being wary of urgent or unusual requests. The Federal Trade Commission offers tips on recognizing phishing scams.
For your customers, it’s beneficial to clearly communicate how your official emails will appear. Educate them on what signs to look for, such as your logo appearing (if BIMI is implemented), proper authentication, and consistent branding. Provide clear instructions on how to report suspicious emails and emphasize that you will never ask for sensitive information via email in an unexpected manner. This proactive communication helps empower your audience to become your first line of defense.
Educate employees
Spot red flags: Teach staff to look for grammatical errors, unusual requests, or generic greetings.
Verify sender: Encourage double-checking sender email addresses and not just display names.
Report quickly: Establish a clear process for reporting suspicious emails to the IT or security team.
Inform customers
Official communication: Clearly state how your brand communicates and what indicators of legitimacy to look for.
Never ask for: Remind users that you won't ask for passwords or sensitive personal data via email.
Direct reporting: Provide an easily accessible and clear method for customers to report suspicious emails.
Protecting your brand's digital identity
Protecting your brand and sender profile from impersonation requires a layered defense. While email authentication protocols like DMARC are fundamental for preventing direct domain spoofing, the more nuanced brand and sender profile impersonation attacks demand a broader strategy. This means going beyond technical configurations to embrace continuous monitoring and comprehensive user education.
By combining robust email authentication, diligent brand monitoring, a structured incident response plan, and consistent education for both employees and customers, you can significantly reduce the risk and impact of impersonation attempts. This comprehensive approach safeguards your reputation and ensures your email communications remain trusted.
Views from the trenches
Best practices
Implement a DMARC 'reject' policy as soon as feasible to prevent unauthorized use of your sending domains.
Regularly monitor DMARC reports to identify sources of unauthorized emails using your brand or domain.
Train all support staff on how to retrieve full email headers from reported impersonation attempts.
Subscribe to partner email lists to detect if they are misusing your brand in their communications.
Common pitfalls
Relying solely on email authentication without monitoring for brand or display name impersonation.
Failing to collect full email headers from user-reported suspicious emails, hindering investigation.
Ignoring 'Reply-To' header impersonation, as it's not protected by standard authentication protocols.
Underestimating the cost and complexity of legal action against botnets involved in impersonation.
Expert tips
Consider getting legal counsel involved if you suspect copyright or trademark infringement through impersonation.
Utilize spam traps to proactively collect intelligence on impersonation campaigns targeting your brand.
Educate users that legitimate emails from your domain will be 'digitally certified' and display your logo (with BIMI).
Establish a clear internal process for handling and escalating impersonation complaints with forensic analysis.
Expert view
Expert from Email Geeks says that BIMI does not directly prevent bad actors from using sender profile information to send spam, as that is the primary function of DMARC.
2022-11-07 - Email Geeks
Expert view
Expert from Email Geeks says that DMARC blocks exact domain impersonations, but will not prevent lookalike domains or impersonation using free email accounts. The expert advises that official domains will have a logo and be digitally certified.
