Prevent Email Spoofing utilizing DMARC

Prevent Email Spoofing technique

Email spoofing remains a primary tactic in phishing attacks, deceiving recipients into trusting emails that falsely appear to be from known sources. Fortunately, DMARC (Domain-based Message Authentication, Reporting, and Conformance) allows domain owners to protect their brand and users by authenticating their emails and blocking unauthorized messages. Here’s a clear guide to set up DMARC to prevent email spoofing on your domain.

What is DMARC?

DMARC is an email authentication protocol that builds upon SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) to verify that messages truly originate from your domain. When an email fails to meet these standards, DMARC enforces a policy on what to do with those messages—either monitor, quarantine, or reject them entirely. Setting up DMARC also allows you to receive reports on who’s sending email on behalf of your domain, aiding in preventing phishing attempts.

How to Set Up DMARC for Your Domain

  1. Access Your Domain’s DNS Settings
    To begin, log in to your domain’s hosting provider or DNS management console, where you’ll add a DMARC TXT record.

  2. Create a DMARC Record
    DMARC records are typically added as TXT records to your DNS settings. Here’s a sample record to get started:

				
					_dmarc.yourdomain.com   IN   TXT   "v=DMARC1; p=none; rua=mailto:dm***********@yo********.com" data-original-string="vEN9v9MWDD80Etv8y6B0VA==a5f2LtJtUXAzqW05mcvrQZHvgy8J/3/sdVQWadpmu1eDMM=" title="This contact has been encoded by Anti-Spam by CleanTalk. Click to decode. To finish the decoding make sure that JavaScript is enabled in your browser.; ruf=mailto:dm************@yo********.com" data-original-string="t4yoMYVpIyKsN1sRS3LHEA==a5fV/B8iMGtBUivDzucetEhWWJBsPsK4xNKK5MD5d5N9kI=" title="This contact has been encoded by Anti-Spam by CleanTalk. Click to decode. To finish the decoding make sure that JavaScript is enabled in your browser.; sp=none; adkim=r; aspf=r; pct=100"
				
			

Explanation of Key Tags:

  • v=DMARC1: Specifies the DMARC protocol version.
  • p=none: Policy to monitor emails initially. Options include:
    • none: No action; monitor only.
    • quarantine: Send suspicious emails to spam.
    • reject: Block unauthenticated emails.
  • rua and ruf: Email addresses where aggregate (rua) and forensic (ruf) reports are sent, helping monitor and analyze potential unauthorized usage.

Best Practice: Start with p=none to gather data on email flows before applying stricter policies like quarantine or reject.

  1. Save and Monitor Your DMARC Record After adding the DMARC record, save changes, and allow 24-48 hours for DNS propagation. During this period, monitor aggregate reports to identify any unauthorized usage of your domain for spoofing attempts.
  1. Set Up Cross-Domain Reporting (if needed) If you prefer receiving DMARC reports on a different domain (e.g., internetmarketinglight.com instead of yourdomain.com), specify the desired email in the rua and ruf tags, like this:
				
					rua=mailto:dm***********@in********************.com" data-original-string="LONYSsLdwlx8zKVp5FXMww==a5famtvHaGyE4zdu8QeZL5UE8inVu3Bb4tDNvGIHIAnj4Mm65Dx3+nRRG9ZL2/sLNW2" title="This contact has been encoded by Anti-Spam by CleanTalk. Click to decode. To finish the decoding make sure that JavaScript is enabled in your browser.
ruf=mailto:dm************@in********************.com" data-original-string="y5Yrx/7b0Z+mSRW4sMiZyg==a5fxO8xYbkVt8FteI/ayr/ONvCz1srqYE7qqbviEOU1o9ObXfxy2ncnpwj6wqoxuPni" title="This contact has been encoded by Anti-Spam by CleanTalk. Click to decode. To finish the decoding make sure that JavaScript is enabled in your browser.
				
			

Note: DMARC no longer requires special DNS authorization records for cross-domain reporting, simplifying setup. Ensure the receiving domain is configured to accept DMARC reports.

  1. Analyze DMARC Reports
    Use DMARC reports to understand who is sending emails from your domain and identify potential spoofing activity. Reports can be checked through DMARC analysis tools like DMARCLY or Google Postmaster Tools.
  1. Update DMARC Policy as Needed
    Once confident in your email flows, adjust the DMARC policy from p=none to p=quarantine or p=reject for more effective email security. Gradually increasing enforcement reduces the risk of blocking legitimate emails while ensuring protection against spoofing.

Why DMARC is Essential for Email Security

DMARC secures your domain by preventing cybercriminals from exploiting your brand through email spoofing. With DMARC policies in place, domain owners gain transparency over email authentication, making it harder for bad actors to misuse their domain in phishing scams. Strengthening DMARC with SPF and DKIM makes for a robust email security strategy that builds trust with users and prevents unauthorized email distribution.

Best Technique to Prevent Email Spoofing

Email is the key to your customer communication strategy. But, what is your email reputation? Email spoofing is a technique used in spam and phishing attacks to trick users into thinking a message came from a person or entity they either know or can trust. In spoofing attacks, the sender forges email headers so that client software displays the fraudulent sender address, which most users take at face value. To prevent email spoofing, setting up and managing your DMARC (Domain-based Message Authentication, Reporting, and Conformance) configuration is the key to getting insight into your email delivery. DMARC is a mechanism that ties SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) together to help domain owners prevent email spoofing by telling receiving mail servers how to handle mail that claims to come from your domain that did not align with your SPF or DKIM records specifications. The way this works, the sending organization (your mail server) publishes a DMARC record to DNS (Domain Name System) that explains what to do with emails that fail (SPF or DKIM) or are questionable by either rejecting or quarantining the email. An added benefit of DMARC is that you can set it to receive reports from the recipient server that tell you exactly how your domain is being used. These reports are labeled forensic reports and aggregate reports.

Lock your domain down and ensure only authorized servers are sending mail on behalf of your domain by following these steps:

NOTE: SPF and DKIM are automatically setup on your cPanel when you add a domain or subdomain so we will only focus on DMARC setup here. So let’s begin the setup to prevent email spoofing:
  1. In your cPanel locate and enter DMARC in Hosting Tools section. Prevent Email Spoofing utilizing DMARC - DMARC in Hosting Tools
  1. Inside DMARC Settings, select your domain to modify. Prevent Email Spoofing utilizing DMARC - DMARC Settings
  1. On the next screen select the appropriate policy settings you wish your server to perform when an email that fails to meet SPF and DKIM records specifications (likely a spoofed email). Personally I want to reject all failed emails. Here you can also select “NONE” if you wish to only get the reports to see how emails sent in your domain’s name are behaving. Note that if you have other servers sending emails in your domain’s name (i.e. MailerLite) and are not listed in your SPF records, chances are that you will be blocking them from being delivered to the intended mailbox if you select to reject or quarantine those email. So monitoring the traffic beforehand for some time by selecting “NONE” may be a valuable decision. Prevent Email Spoofing utilizing DMARC - DMARC policy settings
  1. Now click UPDATE. Prevent Email Spoofing utilizing DMARC - DMARC settings
  1. Next, we will go to the Zone Editor to make final adjustments to the DMARC policy we just created. Prevent Email Spoofing utilizing DMARC - DMARC settings in Zone Editor
  1. Ensure you are picking the domain you’re working with (if you have more than one in your list) then click Manage. Prevent Spam and Phishing attacks utilizing DMARC - Manage DMARC settings in Zone Editor
  1. In the Filter section click the TXT option. Prevent Spam and Phishing attacks utilizing DMARC - Filter section in Zone Editor
  1. Now look for an entry that starts out with _dmarc.yourdomain.com and in this section you’ll find all the options available for this DMARC policy. Ensure you also include your email address(s) for Aggregate and Failure Reports to be sent to you on a regular basis. Prevent Spam and Phishing attacks utilizing DMARC - options available for this DMARC policy
  1. Last thing is to hit the Save Record button and the process will be complete.
To check your setup visit https://dmarcly.com/tools/dmarc-checker, enter your domain name and hit the “Check DMARC Record” button. Reports will be sent to your email in a .gz (zipped) format which if you unzip you will have an XML file format that can be easily viewed in Excel or utilizing a site like https://dmarcadvisor.com/dmarc-analyzer. Alright! You have successfully secured your emails from future spoofing utilizing the DMARC policy setup. Hope you made it to the end without any problems but if you need any help setting up your server to prevent email spoofing, don’t hesitate to reach out and I’ll be happy to help out! 🙂

UPDATE 7.27.2022

Perhaps you have several domains and wish to receive the DMARC reports at a single email from a specific domain. For example, you have Domain1.com, Domain2.com, Domain3.com and you want all 3 domains to send the reports to re*****@Do*****.com . So in this case setup the DMARC as shown above and include re*****@Do*****.com as an email on all domain records. HOWEVER, in order for this to work we’ll also have to setup an EDV (External Destination Verification) on Domain1.com. So here’s how you do this. Go to Domain1.com cPanel and setup a separate record in your Zone Editor as follows: TYPE TXT NAME *._report._dmarc.domain1.com RECORD v=DMARC1 Obviously in the example above you substitute domain1.com for the domain you wish to accept the DMARC reports. The * indicates that any domain is allowed to send DMARC reports to domain1.com. And that should do it! Well if this was useful or simply too much to follow let me know in a comment below. You can always click here and I’ll be happy to give you a helping hand. 🙂

4 Responses

  1. This article is a must-read for anyone concerned about email security! Implementing DMARC to prevent email spoofing is a crucial step for protecting your domain, and this guide explains it clearly and effectively.

  2. Preventing email spoofing with DMARC is crucial for maintaining email security. This article does a great job explaining DMARC and its implementation. Very informative and practical!

  3. The step-by-step instructions on setting up DMARC are very helpful. It’s important to safeguard emails, and this guide provides a clear roadmap to do so. Thanks for sharing!

  4. Implementing DMARC not only prevents spoofing but also improves email deliverability. This guide is an excellent resource for anyone looking to secure their email communications. Great work!

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