Understanding DMARC

Security tips

Jul 25

A Simple Guide for Small Business Owners

What is DMARC?

DMARC stands for Domain-Based Message Authentication, Reporting, and Conformance. It is an email authentication protocol designed to protect your email domain from being used in phishing and spoofing attacks. Essentially, DMARC helps ensure that emails sent from your domain are legitimate and helps prevent cyber-criminals from using your domain to send fraudulent emails.

Why are DMARC Records Important?

Protect Your Brand: DMARC helps protect your brand's reputation by preventing malicious actors from sending fake emails that appear to come from your domain.
Increase Email Deliverability: By implementing DMARC, you can improve the chances that your legitimate emails will reach your customers' inboxes instead of being marked as spam.
Gain Visibility: DMARC provides detailed reports about who is sending emails on behalf of your domain, giving you insight into potential abuse and unauthorized usage.

How to Set Up DMARC Records

Setting up DMARC records might sound technical, but it's a crucial step in securing your email communications. Here’s a step-by-step guide to help you get started:

Understand the Components of a DMARC Record:
- Policy (p): This tells email receivers what to do with emails that fail DMARC checks. The policies are:
  - none: No specific action is taken, but reports are sent.
  - quarantine: Emails that fail DMARC checks are marked as spam.
  - reject: Emails that fail DMARC checks are rejected outright.
- Reporting (rua): This specifies where to send aggregate reports about DMARC activity.
- Forensic Reporting (ruf): This specifies where to send detailed reports about emails that fail DMARC checks.
Create Your DMARC Record:
- A DMARC record is a TXT record added to your domain’s DNS settings. Here’s an example of a simple DMARC record:
```
css
```

Here is an example with a breakdown

v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:dmarc-forensics@yourdomain.com; pct=100; sp=none; aspf=r;

Breakdown of the DMARC Record Components:

v=DMARC1: This specifies the version of DMARC being used.
p=quarantine: This indicates the policy for emails that fail DMARC checks. In this case, quarantine means that emails failing the checks should be treated as suspicious and sent to the spam/junk folder.
rua=mailto
@yourdomain.com: This is the email address where aggregate reports are sent. These reports provide an overview of email traffic and DMARC results.
ruf=mailto
@yourdomain.com: This is the email address where forensic reports (detailed failure reports) are sent. These reports provide detailed information about individual email failures.
pct=100: This specifies the percentage of emails to which the policy is applied. In this case, 100 means the policy is applied to all emails.
sp=none: This is the policy for subdomains. Here, none means no specific action is taken for emails sent from subdomains.
aspf=r: This specifies the alignment mode for SPF (Sender Policy Framework). r stands for relaxed alignment, meaning the SPF check is more lenient.

How to Implement This DMARC Record

Log in to Your Domain Registrar’s Account:
- Go to the DNS management section of your domain registrar’s website.
Add a New TXT Record:
- Name: _dmarc
- Type: TXT
- Value: v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:dmarc-forensics@yourdomain.com; pct=100; sp=none; aspf=r;
Save the Changes:
- Ensure you save the changes to update your DNS settings.

Summary

This example DMARC record is a powerful tool for protecting your domain from email spoofing. By specifying how to handle emails that fail DMARC checks and where to send reports, you can gain valuable insights into your email traffic and enhance your email security.