Maliscanner not checking SPF ?

[Giovanni Panozzo]

I'm running Mailscanner v5.1.3-2 on Ubuntu 18.04.

Every incoming e-mail is marked with spamassassin's T_SPF_HELO_TEMPERROR.

i.e:
x-myorg-myorg-mailscanner-spamcheck: non spam,	SpamAssassin 
(punteggio=1.868, necessario 6, BODY_SINGLE_WORD 1.86, 
T_SPF_HELO_TEMPERROR 0.01)


And it seems also that spamassassin is unable to perform the SPF check: 
all e-mail originatinig from not SPF allowed IP address are not detected 
as spam.

How can I debug T_SPF_HELO_TEMPERROR? Any idea?

Thank you.