The standard configuration of qmail uses dot-forward to emulate sendmail .forward mecanism (see net-mail/qmail/files/1.03-r7/defaultdelivery) but qmail does'nt depend on net-mail/dot-forward ... This dependency should be added or the default delivery mechanism changed not to use dot-forward ...
We've taken the policy not to install any additional qmail packages from the qmail ebuild. The qmail-sumo is there for that purpose.