Package: ssmtp

"ssmtp" package binaries on CentOS:

/usr/bin/mailq /usr/bin/mailq.ssmtp /usr/bin/newaliases /usr/bin/newaliases.ssmtp /usr/sbin/sendmail /usr/sbin/sendmail.ssmtp /usr/sbin/ssmtp

You may install this package on CentOS with yum install ssmtp

"ssmtp" package binaries on Debian:

/usr/sbin/mailq /usr/sbin/newaliases /usr/sbin/sendmail /usr/sbin/ssmtp

You may install this package on Debian with apt-get install ssmtp