SPF record exceeds the maximum DNS lookup limit

SPF (Sender Policy Framework) is an email security standard that lists which mail servers are authorised to send email on behalf of your domain. DNS lookups are the checks required to verify each entry in that list, and the limit is ten. Exceeding ten lookups causes an outright SPF failure (called a PermError) for every email sent from your domain. Receiving mail servers treat these emails as unauthenticated, meaning your legitimate emails may be rejected or land in spam. Audit your SPF record and flatten it by replacing include: references with their underlying IP addresses, or use an SPF flattening service to stay within the ten-lookup limit automatically.