The information provided below can be found in the SPF RFC located here: http://tools.ietf.org/html/rfc7208#section-2.6
A result of “none” means either (a) no syntactically valid DNS domain name was extracted from the SMTP session that could be used as the one to be authorized, or (b) no SPF records were retrieved from the DNS.
A “Neutral” result means the ADMN has explicitly stated that it is not asserting whether the IP address is authorized.
A “Pass” result is an explicit statement that the client is authorized to inject mail with the given identity.
SPF = Fail:
A “Fail” result is an explicit statement that the client is not authorized to use the domain in the given identity.
A “Softfail” result is a weak statement by the publishing ADMD that the host is probably not authorized. It has not published a stronger, more definitive policy that results in a “fail”.
A “Temperror” result means the SPF verifier encountered a transient (generally DNS) error while performing the check. A later retry may succeed without further DNS operator action.
A “Permerror” result means the domain’s published records could not be correctly interpreted. This signals an error condition that definitely requires DNS operator intervention to be resolved.