SPAMCONTROL is an extension qmail. Though mainly used to filter and control unsolicited commercial E-Mails (UCE/SPAM), since release 2 it includes substantial EMSTP protocol enhancements for qmail.
Qmail-Scanner is an add-on that enables a Qmail email server to scan gatewayed email for certain characteristics (i.e. a content scanner). It is typically used for its anti-virus and anti-spam protection functions, in which case it is used in conjunction