Deep-dive into your SPF record. Visualize recursive includes, check DNS lookup limits, and validate syntax against RFCS.
RFC 7208 imposes a hard limit of 10 DNS lookups to prevent Denial of Service (DoS) attacks on email receivers. If your record exceeds this, legitimate emails may land in spam or be rejected with a PermError.
Mechanisms like include, a, mx, ptr, and exists count as 1 lookup each. ip4, ip6, and all do not count towards the limit.