If you have spotted that some of your emails have failed SPF (Received-SPF: PermError) due to invalid mechanism, here are some things that you may have caused this and you need to double check:
When constructing an SPF record using an SPF record generator do not copy and paste the results, type them manually carefully.
Check your SPF record closely for invalid characters, sometimes they may be hard to spot.
Check your SPF record for outdated entries as some receivers may treat your whole record as invalid if for example one of your “include” statements includes outdated information.
Do not use “+” qualifier in front of your mechanisms as it is already implied.