I was looking at how various sites have their SPF records set, and found a site whose SPF record ends with
This seems to be a bad idea, and spf-all says the following about the matter:
+all Pass The email is never a forgery. This option should not be used.
Yet I cannot find anything in the RFC that says this is banned, so it appears to be a valid record.
Is this a valid record? And if so, would most spam filters treat this as an indication to raise the required level of spammyness of a message from this domain before it is treated as spam, or would it simply ignore the record, or count it against the domain?