Example amavisd-new + qmail QMQPqq configuration:


                      ==========================================
                     /                                          \
                    ||                                          ||
                    \/                                          ||
                 port 25 (127.0.0.2)   port 10628 (127.0.0.2)   ||
  Internet   ---------------   qmail-qmqpc   ---------------    ||
===========> | qmail-smtpd | ==============> | amavisd-new | ====
  Clients    ---------------                 ---------------
           port 25    ||
                      ||
                      \/
               --------------- 
               | qmail-queue |                  
               ---------------
                      ||
                      ||
                     /  \
      Internet <=====    =====> Mail hosts




or alternatively if dedicated qmail-smtpd for amavisd-new is present:


         
                                       port 10628 (127.0.0.2)
  Internet   ---------------   qmail-qmqpc   ---------------
===========> | qmail-smtpd | ==============> | amavisd-new | ====
  Clients    ---------------                 ---------------    ||
           port 25                                              ||
                                                                /
                       /========================================
                      ||
                      \/ port 10025 (127.0.0.2)
   -----------------------------------------------
   | qmail-smtpd-just-for-our-lovely-amavisd-new |
   -----------------------------------------------
                      ||
                      ||
                      \/
               --------------- 
               | qmail-queue |                  
               ---------------
                      ||
                      ||
                     /  \
      Internet <=====   =====> Mail hosts