Configuracion de ssmtp con gmail

aptitude install ssmtp

vi /etc/ssmtp/ssmtp.conf

#
# Config file for sSMTP sendmail
#
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
#root=postmaster
root=usuario@gmail.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=mail
mailhub=smtp.gmail.com:587

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

# The full hostname
#hostname=host.localdomain
hostname=usuario@gmail.com

UseTLS=YES
UseSTARTTLS=YES
AuthUser=usuario
AuthPass=password

# 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=NO
FromLineOverride=YES

vi /etc/ssmtp/revaliases

 # sSMTP aliases
#
# Format:   local_account:outgoing_address:mailhub
#
# Example: root:your_login@your.domain:mailhub.your.domain[:port]
# where [:port] is an optional port number that defaults to 25.
root:usuario@gmail.com:smtp.gmail.com:587