What is DMARC? A Simple Guide for Businesses
Email is one of the most important tools in business, but it’s also one of the most abused. Every day, hackers send billions of fake emails that pretend to come from trusted companies. These spoofed emails trick people into sharing passwords, wiring money, or downloading malware.
That’s where DMARC comes in.
DMARC is an email security standard that helps stop spoofing and makes sure email really comes from who it says it does. Along with SPF and DKIM records, DMARC has become an essential part of protecting your business from phishing attacks and improving email deliverability.
In this article, we’ll explain DMARC in plain English—what it is, how it works, why it matters, and how businesses can get set up properly.
What is DMARC?
DMARC stands for Domain-based Message Authentication, Reporting, and Conformance.
It’s a rule you put in place for your domain name (like “yourbusiness.com”) that tells receiving mail servers what to do if an email fails authentication checks.
Think of DMARC as a bouncer at the door of your brand’s email. If someone shows up claiming to be you but can’t prove it, DMARC decides whether to let them in, watch them carefully, or kick them out.
With DMARC, you can:
- Protect against spoofing: Block fake emails pretending to come from your company.
- Get reports: See who is trying to send emails using your domain.
- Improve trust: Ensure your legitimate emails actually land in inboxes instead of spam.
How DMARC Works
DMARC builds on two other systems—SPF and DKIM. These are like ID checks that prove your email is authentic. DMARC ties them together and enforces rules.
Here’s the process step by step:
- You publish DMARC, SPF, and DKIM records in your domain’s DNS settings.
- When you send an email, the receiving mail server (like Gmail, Outlook, Yahoo) checks:
- Does the email come from an approved sender (SPF)?
- Is the message digitally signed and untampered (DKIM)?
- DMARC evaluates the results. If the email fails, DMARC applies your policy:
none→ Take no action, just report.quarantine→ Mark as spam or suspicious.reject→ Block it completely.
SPF: Sender Policy Framework
SPF is the first building block.
With SPF, you create a list of servers that are allowed to send emails for your domain. Think of it as an “approved senders list.”
For example, if your email is hosted on Microsoft 365, you add Microsoft’s servers to your SPF record. If you use Mailchimp for marketing, you add them too.
When someone receives your email, their server checks your SPF record. If the email comes from a server not on the list, it fails.
Key point: SPF only works if the email is sent from a listed server. If a hacker sends from somewhere else, SPF blocks it.
DKIM: DomainKeys Identified Mail
DKIM is the second building block.
With DKIM, your outgoing email gets a digital signature—like a wax seal on a letter. When the receiving server gets the email, it verifies the seal against your domain’s DKIM record.
If the seal matches, the email hasn’t been tampered with and is truly from you. If not, it fails.
Key point: DKIM proves the email hasn’t been altered and that it was authorized by the domain.
How DMARC Uses SPF and DKIM Together
SPF and DKIM each help, but they’re not perfect on their own. Hackers can sometimes bypass them. DMARC makes them stronger by combining the checks.
For an email to pass DMARC, at least one of SPF or DKIM must pass, and the domain must align with the “From” address. In other words, the visible “From” address people see must match the technical sender domain.
Without DMARC, a hacker could pass SPF or DKIM but still make the email look like it’s from your domain. With DMARC, that trick fails.
Why DMARC is Becoming a Requirement
Not long ago, DMARC was “nice to have.” Now, it’s becoming a must-have.
Big providers like Google and Yahoo have announced that businesses sending bulk emails must have DMARC, SPF, and DKIM in place. Without them, your emails may go straight to spam—or get rejected entirely.
Even outside of compliance, the benefits are clear:
- Protect your reputation – Customers trust your emails when they know they’re authentic.
- Avoid phishing attacks – Stop criminals from impersonating your domain.
- Improve deliverability – Ensure marketing, invoices, and notifications actually reach inboxes.
- Meet compliance – Many industries (finance, healthcare, legal) are requiring it as part of cybersecurity standards.
Don’t Forget Third-Party Tools
Most businesses don’t just send email from Outlook or Gmail. You probably use other tools:
- CRMs like Salesforce or HubSpot
- Marketing platforms like Mailchimp or Constant Contact
- Document platforms like DocuSign or Adobe Sign
- Helpdesk systems like Zendesk or Freshdesk
Each of these tools may send emails on your behalf, using your domain name. If they’re not set up in your SPF and DKIM records, their emails may fail DMARC and end up in spam—or be rejected.
That’s why proper configuration is critical. Every tool that sends on behalf of your company must be authenticated.
What Happens If You Don’t Set Up DMARC?
If you ignore DMARC, here’s what you risk:
- Spoofing attacks – Hackers can send fake invoices or phishing emails that look like they’re from your business.
- Spam folders – Even your legitimate messages may get flagged as suspicious.
- Lost trust – Customers may fall for fake emails or stop opening yours.
- Compliance problems – Some industries and vendors require DMARC for partnerships.
The bottom line: without DMARC, your email security is incomplete.
Setting Up DMARC, SPF, and DKIM
Getting started involves updating your domain’s DNS settings. At a high level:
- SPF – Create a record listing all servers and services allowed to send email for your domain.
- DKIM – Enable signing in your email system and publish the public key in DNS.
- DMARC – Publish a policy that tells receiving servers what to do with failing emails (
none,quarantine,reject).
Many companies start with none to monitor, then move to stricter enforcement as they gain confidence.
The Reporting Advantage
One overlooked benefit of DMARC is reporting.
When you enable DMARC, you can receive daily reports showing:
- Which servers are sending email for your domain
- Which emails are passing or failing SPF and DKIM
- Where spoofing attempts are coming from
This gives you visibility into both legitimate and malicious use of your domain.
Making Email Safer and Stronger
At its core, DMARC is about trust. Businesses need to know their emails are reaching inboxes safely, and customers need to know they can trust what they open.
By setting up SPF, DKIM, and DMARC properly, you strengthen your brand, reduce phishing risk, and future-proof your email systems.
Final Thoughts: Don’t Wait to Implement DMARC
Email is still the most common attack vector for cybercriminals, and the risks are only growing. DMARC is one of the most effective ways to stop them.
It’s no longer optional—it’s the new standard.
Need Help?
Configuring SPF, DKIM, and DMARC can be tricky, especially if you use multiple tools like CRMs, marketing platforms, or e-signature services. Misconfigurations can cause deliverability issues—or leave you exposed to spoofing.
If you’d like expert help setting up or troubleshooting your email authentication, reach out to Urban IT today at (818) 914-5152 or [email protected]. We’ll make sure your email is secure, trusted, and delivered.