SPF lookup limits
RFC 7208 §4.6.4 limits an SPF evaluation to 10 DNS‑lookup mechanisms. The mechanisms that count are include, a, mx, ptr, exists, and the redirect modifier. ip4, ip6 and all are free.
- Exceed 10 and receivers return
permerror. - More than 2 "void" lookups (empty results) is also a permerror.
- A single TXT string can't exceed 255 bytes; longer records are split into multiple strings.
Solid SPF computes your lookup count before and after flattening so you can see the improvement.