/usr/bin/mailq
/usr/bin/newaliases
/usr/bin/rmail
/usr/sbin/postalias
/usr/sbin/postcat
/usr/sbin/postconf
/usr/sbin/postdrop
/usr/sbin/postfix-add-filter
/usr/sbin/postfix-add-policy
/usr/sbin/postfix
/usr/sbin/postkick
/usr/sbin/postlock
/usr/sbin/postlog
/usr/sbin/postmap
/usr/sbin/postmulti
/usr/sbin/postqueue
/usr/sbin/postsuper
/usr/sbin/posttls-finger
/usr/sbin/qmqp-sink
/usr/sbin/qmqp-source
/usr/sbin/qshape
/usr/sbin/rmail
/usr/sbin/sendmail
/usr/sbin/smtp-sink
/usr/sbin/smtp-source
You may install this package on Debian with
apt-get
install postfix