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Q & A Email Auth · August 12, 2026

What is the SPF 10-lookup limit?

SPF evaluation can trigger at most 10 DNS lookups (include:, a:, mx:, ptr:, exists: each count). Exceeding 10 lookups causes a PermError. Modern email service providers often chain several includes together, making it easy to hit this limit. Use SPF flattening tools or ip4:/ip6: mechanisms instead of includes where possible.

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What Is an SPF Record? Sender Policy Framework Explained
SPF tells the world which servers are allowed to send email on behalf of your domain. A missing or misconfigured SPF record lets spammers forge your address — and sends your legitimate email straight to spam.
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