"Is it possible to send an email from a host that has no email
client software installed? As long as you have netcat, of course it
is!
"Netcat (/usr/bin/nc on Red Hat Enterprise Linux systems) is a
simple utility for reading and writing data across TCP/UDP
connections. It's often used for testing and debugging network
connections. In its most basic usage, netcat allows you to feed a
stream of data to a specific port on a specific host, which is
perfect for our purpose here. Check the netcat man page for more
information on it's various features. There are also sample scripts
under /usr/share/doc/nc-*/. If netcat is not installed on your Red
Hat Enterprise Linux, CentOS or Fedora system, you can install it
with the command yum install nc."