SpamFoo appears to do something with SPF/DKIM/DMARC, although the details are unclear.   In many cases, SmarterMail or some other calling program will have already performed this analysis.  The /classify function should allow the calling program to supply already-known authentication results.   This serves two purposes:

- It avoids redundant processing.

- If the calling program has already adjusted authentication results based on local policy, passing those results to SpamFoo will permit it to correctly evaluate the message based on the calling program's data..