Definition
DMARC (Domain-based Message Authentication, Reporting, and Conformance) tells receiving ISPs what to do with email that fails SPF and DKIM checks. Setting up DMARC involves publishing a DNS record that specifies your policy and a reporting address.
Setup Stages
- p=none (monitoring): Start here. ISPs send you reports on authentication failures but take no action. Run for 2-4 weeks to identify legitimate sending sources that might fail authentication.
- p=quarantine: Move to quarantine once you have identified and fixed authentication gaps. ISPs send failing mail to spam instead of blocking it.
- p=reject: Full enforcement. ISPs reject email that fails authentication. This is the goal — it prevents domain spoofing entirely.
DNS Record
A DMARC record is published as a TXT record at _dmarc.yourdomain.com and looks like: v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:dmarc-forensics@yourdomain.com; pct=100.
Related Glossary Terms
AOL Mail for Email Marketers
AOL Mail is a legacy email provider with specific deliverability requirements and rendering quirks, now operating as part of the Yahoo+AOL network under shared infrastructure.
BIMI
BIMI (Brand Indicators for Message Identification) is an email standard that allows brands to display their logo next to their emails in supported email clients. It requires DMARC enforcement at quarantine or reject policy.
Bounce Rate Threshold
A bounce rate threshold is the percentage of hard or soft bounces at which email platforms and ISPs begin to penalise sender reputation, typically around 2-5%.
Bounce Rate
Email bounce rate is the percentage of emails that were rejected by the receiving server before reaching the recipient. It is a key indicator of list health and data quality.
Email Deliverability
Email deliverability is the ability to land in the recipient's inbox rather than the spam folder. It depends on sender reputation, authentication, list quality, and content practices.
DKIM (DomainKeys Identified Mail)
DKIM (DomainKeys Identified Mail) is an email authentication method that uses digital signatures to verify that an email was not tampered with during transit and comes from a authorised domain.