SPF
Check your SPF record.
SPF names the servers allowed to send as your domain. This checker reads the record, counts the DNS lookups recursively through every include, and grades how it ends.
Questions
The details.
What is an SPF record?
A TXT record starting v=spf1 that lists which servers may send email as your domain. Receivers check the sending server against the list. Mail from anywhere else fails SPF — and if DKIM does not pass in alignment either, a DMARC policy junks or rejects it.
What is the SPF 10-lookup limit?
SPF processing allows at most 10 DNS lookups per check, counted through every include, a, mx, ptr, exists and redirect \u2014 recursively. Every SaaS tool you authorise spends lookups, and past 10 the record returns a permanent error and stops protecting you. This checker counts them recursively through the include chain; if a chain nests deeper than the scan follows, it says so rather than calling the record healthy.
Should my SPF record end in -all or ~all?
-all tells receivers to hard-fail unauthorised mail; ~all only marks it. Use ~all while testing changes, then move to -all. If your record ends in +all, the entire internet is authorised to send as you \u2014 fix that today.
Can I have two SPF records?
No. The standard allows exactly one; a second record makes SPF permanently fail validation. Merge them into a single v=spf1 line.