How to Set Up DMARC on Microsoft 365 and Prevent Spoofing

Going for a proper Microsoft 365 DMARC setup is crucial for businesses looking to protect their email communications from spoofing attacks. Email spoofing and phishing remain the two largest threats to organizations. Cybercriminals can impersonate trusted brands to deceive employees into clicking on malicious links. This can bypass the security protocols that can lead to compromising of sensitive data and financial transactions. 

The fallout from such attacks can be tragic for businesses, including loss of money, data breaches, and loss of reputation.

If you use Microsoft 365 for your business email, you are already dealing with one of the most attacked platforms on the internet. Microsoft comes with built-in security features, but attackers can still spoof your company’s domain.

This is where DMARC (Domain-based Message Authentication, Reporting, and Conformance) comes into the picture. For Microsoft 365 customers, DMARC is the most effective solution for protecting your company from spoofing as well as saving your brand identity.

What is DMARC?

DMARC is a security measure for your email domain. It works together with two other protocols, SPF and DKIM, creating a three-layer verification system. It also limits your organization’s domain from being used in phishing and spoofing attacks.

SPF provides the list of authorized mail servers that are permitted to send mail on behalf of your domain. DKIM adds an encrypted digital signature to your outgoing emails, allowing receiving mail servers to verify that the message is valid.

DMARC combines SPF and DKIM results and tells receiving mail servers what to do with messages that fail authentication. For example, you can tell them to:

• None: Just monitor, do nothing.
• Quarantine: Send the suspicious message to the spam folder.
• Reject: Block this spoofed email entirely.

Why Is It Important for Microsoft 365?

Even if your company utilizes Microsoft 365 email security features, your domain itself can still be spoofed if you do not have DMARC configured. Every time a hacker sees a gap, they know they can take advantage of it and send phishing emails and pretend like they come from your official business email address. Microsoft 365 DMARC setup will help you:

• Blocks Brand Impersonation: Keeps attackers from spoofing your domain while carrying out phishing attacks.
• Protects Customers and Partners: Allows any external recipient to trust emails that they receive from your domain.
• Provides Greater Deliverability: Authenticated email is less likely to be categorized as spam by the receiving mail servers.
• Provides Visibility: DMARC reporting will provide you an insight into what is sending email on behalf of your domain.

For example, someone impersonating your company’s CEO is phishing your company’s finance team to process a wire transfer. With no DMARC protection, the original email could potentially slip through spam filters because it looks legitimate and goes straight to that recipient’s inbox.

If DMARC is enforced (set to “reject”), the receiving mail server will immediately reject the email upon leaving the originating mail server, and your employee will never even see the spoofed email. The most critical issue is not the company losing money but instead preventing it from losing its brand and losing customers’ trust.

Prerequisites for Setting Up DMARC on Microsoft 365

Before you can configure DMARC with Microsoft 365, you need to make sure multiple setup requests are met. This often leads users to incomplete setups and eventually delivery issues. 

Microsoft 365 Admin Role 

You will need to be an admin within the Microsoft 365 Admin Center. This will help you configure different email authentication settings, like DKIM, and also enable you to check whether your domain is properly registered with Microsoft 365.

DNS Management

As you are aware, DMARC, SPF, and DKIM are all published by DNS TXT records. Therefore, you will need access to your domain registrar or DNS hosting provider. With no access at the DNS level, you will not be able to publish or amend the records that are used by email servers for verifying your messages.

SPF and DKIM Requirements

DMARC depends on SPF and DKIM to verify emails. SPF authorizes mail servers, like Microsoft 365, to send emails with your domain name. DKIM provides a digital signature on every message. Both of these must be in place to allow DMARC to operate correctly.

Step-by-Step Guide: Setting Up DMARC on Microsoft 365 Business Email

Getting DMARC operational through Microsoft 365 DMARC setup is a very simple and direct process as long as you have the required access and prerequisites squared away first. Follow these steps to fully configure and secure your domain. This will help you prevent email spoofing Microsoft 365.

Log in to Microsoft 365 Admin Center

Go to admin.microsoft.com and sign in with your Microsoft 365 global admin credentials. Only those users with the appropriate admin permissions can configure email authentication policies and the domain settings.

Go to your DNS settings

From the Admin Center dashboard:

1. Select Settings > Domains.
2. Select the domain to add DMARC security to it.
3. Microsoft 365 will provide details on where you manage your domain’s DNS settings. Usually, you will manage your DNS directly at your domain registrar. If your DNS is hosted elsewhere, you will need to log in with that provider to make any modifications. 

Create the DMARC Record in your DNS

After logging in to your DNS management console, create a new TXT record using the following details:

Host/Name: _dmarc.yourdomain.com

Value (DMARC Policy): v=DMARC1; p=quarantine; rua=mailto:[email protected]

Important: Start with p=none for monitoring purposes. After reviewing reports and confirming that legitimate emails pass authentication, you can progress to p=quarantine or p=reject.

Save and Verify

Now save your changes after creating the DMARC record, as it could take a few hours or more for DNS propagation. Once you have live DNS changes, you can help verify your setup using things like Threatcop’s spoof check tool, and it will confirm whether your domain is safe from spoofing attempts.

Start checking your domain today with Threatcop’s email spoof check tool to ensure your domain is safe from spoofing.

How to Determine if Your Microsoft 365 Email Domain Is Vulnerable to Spoofing

Once you have created your SPF, DKIM, and DMARC records, you would like to validate if your Microsoft 365 email domain is protected against spoofing attempts, and one of the best and simplest ways to do that is with Threatcop’s Email Spoof Check Tool.

The spoof check tool scans your domain’s email authentication implementation, such as SPF, DKIM, and DMARC, to determine if an attacker could spoof your business email. The tool crawls your domain’s DNS records and will pinpoint any weaknesses or omissions in your setup.

To confirm if your Microsoft 365 email domain is safe from spoofing and phishing, try Threatcop’s Email Spoof Check Tool now! 

Common Mistakes to Avoid When Setting Up DMARC

DMARC is a great ally in the protection of your Microsoft 365 email domain. However, if any organization gets confused and configures DMARC incorrectly, your policy effectiveness can be undermined. Understanding common mistakes can assist you in a secure and successful Microsoft email authentication.

Incorrect DMARC Record Syntax

A DMARC policy is published and configured with a TXT record in your DNS; even a small typo or misplaced semicolon can negatively impact your entire email authentication.

For instance, if you enter p=Quarantine instead of p=quarantine, you could be leaving your domain open to abuse. Always verify the format using a DMARC validator tool before publishing your record.

Not Setting Up SPF/DKIM First

DMARC relies on SPF and DKIM to work. Otherwise, your published DMARC policy is just decoration. That means messages could be failing storage even when they are legitimate. Before you publish anything to DMARC, you should verify that your SPF includes all authorized senders.

Not Monitoring DMARC Reports

Another mistake is to publish a DMARC record and completely ignore its reports. DMARC reports provide valuable information on who is spoofing your domain and if your legitimate emails are getting to the inbox or are failing authentication. 

Best Practices for Maintaining Email Security with DMARC

Setting up DMARC on Microsoft 365 is just the first part of it all. You need to properly maintain it to ensures long-term security effectiveness.

1. Regular Monitoring

DMARC reports will show you who is sending emails from your domain or potentially sending emails with it and if they passed SPF/DKIM checks. These reports should be reviewed routinely, and by doing so you can address spoofing attempts earlier and identify unauthorized senders sooner. Using your mailbox or reporting will help to make that easier.

2. Incremental Policy Implementation

Implement DMARC in increments. First, begin with p=none to monitor traffic without blocking emails. After all legitimate senders are aligned, update the policy to p=quarantine or filter, then p=reject, for maximum protection. Using this incremental approach will allow you to remain in control and ensure that your clients’ and employees’ actual emails are not compromised.

3. Layered Security

DMARC cannot function as a standalone solution; it must operate with the existing Microsoft 365 security solutions, such as Exchange Online Protection and Defender for Office 365. In comparison, the Microsoft 365 anti-phishing filter, multi-factor authentication, and your training on security awareness with DMARC will provide an effective layered defense.

How DMARC Improves Your Microsoft 365 Email Security in the Long Run

Microsoft email authentication through DMARC provides technological safeguards that enhance your organization’s email security and protect your investment in organizational credibility.

Enhanced Reputation

DMARC allows your domain to be more credible by only allowing authorized senders to email on your behalf. Trust is built among your clients, partners, and email service providers.

Business Email Compromise (BEC) Prevention

By blocking unauthorized senders, DMARC reduces “BEC,” where hackers impersonate executives or authorized vendors to steal money or private data. 

Compliance

Regulations such as GDPR and HIPAA guidelines require strong email security practices. Implementing DMARC provides strong email security but also shows organizations are compliant with the standard. This reduces the organization’s risk and liability costs of breaches in legal and regulatory matters.

Conclusion

Both email spoofing and phishing attacks remain among the most destructive threats to businesses. Therefore, Microsoft 365 domains are a prime target. Without safeguards in place, a spoofed email could result in financial loss, a data breach, or reputational damage with just one instance.

Microsoft 365 DMARC setup provides superior protection for your organization and your clients. It restricts your domain from being spoofed to only known senders you have approved for use. It is time to take action and prevent email spoofing Microsoft 365 domains from exposing your domain and organization.

Test your Microsoft 365 domain for spoofing today and secure your email with DMARC using Threatcop’s spoof check tool.