Pull the live SPF TXT record, expand every include, and rebuild it as flat IP addresses under the RFC 7208 limit of 10 DNS lookups.
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SPF flattening replaces the include mechanisms in an SPF record with the IP addresses those mechanisms point to. Every include, a, mx, ptr, exists and redirect mechanism costs a DNS lookup when a receiver checks your mail, and RFC 7208 allows at most 10 lookups in one check. Pass that limit and the check returns a permanent error, so authentication fails even when the record is otherwise correct.
This tool fetches your live record, expands includes recursively, counts lookups the RFC 7208 way, and builds a flattened record from ip4 and ip6 mechanisms. The flattened record needs no extra lookups to work.
A flattened record is a snapshot. If a provider adds or removes sending IPs, the flattened record does not update itself, so re-run this tool on a schedule. Keep one SPF record per domain, and check the length of a long flattened record before you publish it.
Flattening turns include mechanisms into the IP addresses behind them, so receivers do not need extra DNS lookups to work out who may send for your domain.
RFC 7208 caps an SPF check at 10 DNS lookups to stop abuse and loops. Over the cap, receivers return a permanent error called PERMERROR and SPF fails.
Yes, if the IPs came from your current record and you publish it as the only v=spf1 TXT record for the domain. Test with the SPF Checker right after publishing.
The SPF Checker audits the record you have. This tool rebuilds that record as flat IP addresses and shows the lookup count before and after.
It expands include and redirect mechanisms recursively, and resolves a and mx mechanisms to IP addresses. ip4 and ip6 terms pass through as they are.
The policy from your original record, such as -all or ~all, is kept at the end of the flattened record. Policies inside included records are dropped.
Yes, from time to time. Providers change sending ranges, and a flattened record only holds the addresses found when you ran the tool.
There is nothing to flatten. Build a record with the SPF Record Generator first, publish it, then flatten it if it needs too many lookups.
No. Flattening fixes lookup count problems. It does not fix typos, duplicate SPF records, a missing record, or a policy that names the wrong senders.
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