Fixing too many DNS lookups: the SPF 10-lookup limit
SPF caps you at 10 DNS lookups, 2 void lookups and 255 characters per string. Cross the line and SPF fails. How to spot it, and how to fix it without breaking mail.
Read postGet SPF and DKIM aligned so DMARC passes
A practical guide to making your return-path and DKIM signing domain match your visible From address, with the common alignment breakers and the fix for each.
Read postSPF, DKIM and DMARC explained without the jargon
The three DNS records behind email authentication, what each one actually proves, and how they work together to stop people forging your domain.
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