This guide explains how to set up DMARC (Domain-based Message Authentication, Reporting & Conformance) for your domain in conjunction with UserDeck, enhancing your email security and deliverability. DMARC builds upon SPF and DKIM, providing an extra layer of protection against spoofing and phishing attacks.
What is DMARC and Why Do You Need It?
DMARC allows you to tell receiving mail servers what to do with emails that fail SPF and/or DKIM checks. This helps prevent malicious actors from forging emails that appear to come from your domain. DMARC also provides reporting mechanisms, giving you insights into email authentication results and potential abuse.
Prerequisites:
- You should have already configured SPF and DKIM for your domain (as outlined in the UserDeck Outgoing Email setup guide).
- Access to your domain's DNS records (usually through your domain registrar or hosting provider).
Steps to Implement DMARC:
Create a DMARC Record: You'll need to create a TXT record for your domain's DNS. The record name should be
_dmarc.yourdomain.com(replaceyourdomain.comwith your actual domain).Define the DMARC Policy: The DMARC record's value defines your policy. A typical DMARC policy consists of tags and their values. Here's a breakdown of the essential tags:
v(Version): Always set toDMARC1.p(Policy): Specifies the action to take for emails that fail SPF and/or DKIM checks. Start withnone(monitor mode) to gather data and then progress toquarantine(mark as spam) and finallyreject(block).rua(Aggregate Reporting URI): Specifies an email address where aggregate reports will be sent. These reports contain statistics about DMARC authentication results. Use a service or tool to analyze these reports. You can use a URI likemailto:dmarc-reports@yourdomain.com.ruf(Forensic Reporting URI): (Optional) Specifies an email address for forensic reports, which provide more detailed information about individual failed emails. Use with caution as these reports can be voluminous. You can use a URI likemailto:dmarc-forensic@yourdomain.com.pct(Percentage): (Optional) Specifies the percentage of emails to which the DMARC policy should be applied. Start with100and gradually decrease as you gain confidence.
Publish the DMARC Record: Add the created TXT record to your domain's DNS.
Example DMARC Record (Monitor Mode):
v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com
This record tells receiving mail servers to monitor emails that fail authentication but not take any action (yet). Reports will be sent to dmarc-reports@yourdomain.com.
Example DMARC Record (Quarantine Mode - 50%):
v=DMARC1; p=quarantine; pct=50; rua=mailto:dmarc-reports@yourdomain.com
This record quarantines 50% of emails that fail authentication.
Example DMARC Record (Reject Mode - 100%):
v=DMARC1; p=reject; rua=mailto:dmarc-reports@yourdomain.com
This record rejects 100% of emails that fail authentication.
DMARC Implementation Stages:
- Monitor Mode (
p=none): Start in monitor mode to collect data and understand the impact of your DMARC policy. Analyze the aggregate reports to identify any legitimate emails that are failing authentication. - Quarantine Mode (
p=quarantine): Once you're confident, move to quarantine mode. This will mark failing emails as spam, but they will still be delivered to the recipient's spam folder. - Reject Mode (
p=reject): After a period in quarantine mode and thorough analysis, move to reject mode. This will block failing emails entirely.
Analyzing DMARC Reports:
Analyzing aggregate reports is crucial to fine-tuning your DMARC policy. These reports provide valuable information about email authentication results and potential issues. Several tools and services are available to help you analyze these reports.
Important Considerations:
- Gradual Implementation: Implement DMARC gradually, starting with monitor mode and progressing to quarantine and reject modes.
- Report Analysis: Regularly analyze DMARC reports to identify and address any issues.
- Patience: Implementing DMARC takes time and careful monitoring.
By following these steps, you can effectively implement DMARC for your domain in UserDeck, significantly improving your email security and deliverability. If you have any questions, please contact our support team.