What Is an SPF Record? How It Works and How to Fix It
An SPF record lists which servers may send email for your domain. Learn the syntax, the 10-lookup limit, common mistakes and how to publish one correctly.
Email authentication
SPF, DKIM and DMARC explained in plain English: what each record does, how to publish it, and how to fix the errors people hit most.
What Is DKIM and How Does It Work?
DKIM adds a cryptographic signature to every email so receivers can prove it came from your domain and was not altered. Learn how it works and how to set it up.
What Is DMARC? A Plain-English Guide to Email Policy
DMARC tells receivers what to do when an email fails SPF and DKIM, and sends you reports. Learn how it works, the policy options and how to publish a record.
SPF "Too Many DNS Lookups": How to Fix the 10-Lookup Limit
SPF allows only 10 DNS lookups. Go over and authentication fails with permerror. Learn how to count lookups, find the culprits and shrink your record.
How to Roll Out DMARC Safely: none, quarantine, reject
Moving straight to p=reject can block your own invoices and newsletters. Follow this staged plan to take a domain from monitoring to full DMARC enforcement.
How to Read DMARC Aggregate Reports (With an Example)
DMARC reports arrive as dense XML. Learn what each field means, how to spot unauthorised senders and which failures to fix first, with a worked example.
SPF Softfail (~all) vs Hardfail (-all): Which Should You Use?
The last characters of an SPF record decide how strictly receivers treat unauthorised senders. Compare ~all, -all, ?all and +all, and choose the right one.
DKIM Selectors and Key Rotation Explained
A DKIM selector lets one domain publish several signing keys. Learn how selectors work, why and when to rotate keys, and how to rotate without losing mail.
How to Check SPF, DKIM and DMARC for Any Domain
Check SPF, DKIM and DMARC with free command-line lookups, email headers and online checkers. Learn what a pass and a fail look like and where each fix belongs.
Put it into practice on your own domain
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