Ssmtp
Installing SSMTP on a node
ssmtp is required for qsub emailing. It's contained in the EPEL (extra packages for enterprise linux) repo but this doesn't seem to be working with RHEL6.
wget http://dl.fedoraproject.org/pub/epel/6/x86_64/Packages/s/ssmtp-2.61-22.el6.x86_64.rpm
rpm -ivh ssmtp-2.61-22.el6.x86_64.rpm
Installs it however.