PREUN
/bin/sh
if [ $1 = 0 ]; then update-alternatives --remove sendmail-command /usr/sbin/nbsmtp fi
POSTIN
/bin/sh
update-alternatives --install /usr/sbin/sendmail sendmail-command /usr/sbin/nbsmtp 5
/bin/sh
if [ $1 = 0 ]; then update-alternatives --remove sendmail-command /usr/sbin/nbsmtp fi
/bin/sh
update-alternatives --install /usr/sbin/sendmail sendmail-command /usr/sbin/nbsmtp 5