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DMARCIAN: SPF Best Practices: Avoiding SPF Record Flattening
- February 24, 2023
- Posted by: Top Deliverability
- Category: DMARC DMARCIAN Email Authentication Email Services Industry News
DMARCIAN just released a engaging write-up:
Why Is SPF Flattening Relevant? SPF has a limit of 10 DNS Lookups; any mechanism (entry) requiring a lookup after the lookup limit will not be evaluated and will fail authentication. In some cases, people turn to SPF flattening tools to work around the 10 DNS lookup limit. When you add a new mechanism in your record, you require a new DNS lookup. The more services and third-parties that send on your behalf, the more complicated and bloated your record can become. SPF record flattening can be an easy answer, but is not the safest route. How Does SPF Flattening Work? In SPF Flattening, hostnames are converted to IP addresses, which don’t count in the DNS lookup tally. Then you create your SPF records using the IP addresses instead of the hostnames. dmarcian developed SPF flattening as an experiment to work around the DNS lookup limit. In IETF’s RFC 7208
Read the original here: SPF Best Practices: Avoiding SPF Record Flattening
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