SmarterMail should add an additional email header explaining X-SmarterMail-TotalSpamWeight calculation or the reason why X-SmarterMail-TotalSpamWeight = 0
For example, we've got an email:
X-SmarterMail-Spam: Reverse DNS Lookup [Passed], ISpamAssassin 0 [raw: 2], SPF_None, DKIM_None, GBUDB, SORBS-RECENT
X-SmarterMail-SpamDetail: 2.8 BAD_CREDIT Eliminate Bad Credit
X-SmarterMail-TotalSpamWeight: 0
(It is a real life example, described here:
)
The additional header could say: "TotalSpamWeight = 0, because the sender is a Trusted Sender"
Or it should say: -14+2+1+1+5+5=0
(In this case we could see that "Reverse DNS Lookup [Passed]" has a negative weight of -14 and should check antispam settings).
Without this header we should make guesses and spend more time looking for the issue reasons.