ssmtp mail relay

sudo aptitude update; sudo aptitude install ssmtp

1. Editar:

sudo cp /etc/ssmtp/ssmtp.conf /etc/ssmtp/ssmtp.conf.bak
sudo vim /etc/ssmtp/ssmtp.conf

Con el siguiente contenido:

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=user1@example.com

# The place where the mail goes. The actual machine name is required no 
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=smtp.gmail.com:587
UseTLS=YES
UseSTARTTLS=YES
AuthMethod=LOGIN
AuthUser=user2@gmail.com
AuthPass=clearpassword

# Where will the mail seem to come from?
#rewriteDomain=

# The full hostname
hostname=mail.local.example.com

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
#FromLineOverride=YES

Ya está, no hace falta reiniciar ningún servicio.