If you have problems with emails not coming from your etherpad deployment try adding the line
smtpServer = localhost:25
to
/usr/local/etherpad/trunk/etherpad/etc/etherpad.localdev-default.properties
and restarting the etherpad daemon
# then
telnet localhost 25
if you get a Connect message then good times, if not, install an MTA such as postfix. By default my box had exim4 on so I did
apt-get remove exim4
# then
apt-get install postfix
Cause I prefer postfix 🙂