Email Security Insights
Expert guides on DMARC, DKIM, SPF, and email authentication best practices to protect your domain from spoofing.
DMARC Adoption in the Top 1,000 Domains (October 2026)
We read DMARC, SPF and BIMI for the Tranco top 1,000 on 19 October 2026. 73.8% of the 688 domains with MX records enforce DMARC; 11.5% publish none.
Email Sender Requirements: Gmail, Yahoo and Outlook
Gmail, Yahoo and Outlook.com require SPF, DKIM, DMARC at p=none or stricter, alignment and one-click unsubscribe from bulk senders. Every rule, cited.
What Is DMARC? How It Works, Policies and Reports
DMARC is a DNS record that tells receivers what to do with mail that fails aligned SPF or DKIM, and where to send reports. How it works, with real records.
DKIM Explained: Signatures, Selectors and Key Sizes
DKIM signs each email with a private key and publishes the public key in DNS. How signing works, the header tags, selectors, key sizes and rotation.
SPF Record Syntax: Mechanisms, Limits and Examples
An SPF record is one TXT record listing the servers allowed to send for your domain. Syntax, qualifiers, the 10-lookup limit and real records.
DMARC Record Syntax: Every Tag, Default and Example
A DMARC record is one TXT record at _dmarc.yourdomain that starts v=DMARC1. Every tag with its RFC 7489 default, plus valid and broken examples.