SPF Check

Fetches a domain's SPF record and expands every include: and redirect= it references, counting the DNS lookups RFC 7208 caps at 10 — the single most common way SPF quietly stops working as senders get added over time.

What this checks

Whether an SPF record exists, and whether there's exactly one (RFC 7208 makes multiple records a hard failure for everyone).
Total DNS lookups across every include:, a, mx, ptr and exists: mechanism, expanded recursively — the count that fails the whole record once it passes 10.
Void lookups (mechanisms pointing at domains with no answer at all) against the separate limit of 2.
Use of the discouraged ptr mechanism, and whether the record ends in a permissive (+all/?all) or missing terminal mechanism.