cat /var/qmail/control/spfbehavior

0 to disable.
1 selects ’annotate-only’ mode, where qmail-smtpd will annotate incoming email with Received-SPF fields, but will not reject any messages.
2 will produce temporary failures on DNS lookup problems so you can make sure you always have meaningful Received-SPF headers.
3 selects ’reject’ mode, where incoming mail will be rejected if the SPF record says ’fail’.
4 selects a more strict rejection mode, which is like ’reject’ mode, except that incoming mail will also be rejected when the SPF record says ’softfail’.
5 will also reject when the SPF record says ’neutral’.
6 if no SPF records are available at all (or a syntax error was encountered).