Using google mail servers as a smarthost from a linux server (ubuntu)

So you want to send mail securely using google's mail servers as a smarthost.

The first thing you'll need is an application specific password for exim.

Once that's created, I will assume the following:

• You are ok with Gmail rewriting your sender address or use this Gmail address.
• Your account name on your local Debian box: YOUR-USER-NAME
• Your host name in /etc/hostname: hostname1
• Your host name in the 127.0.1.1 line of /etc/hosts: hostname1.localdomain hostname1
• Your envelope address is SMTPAccountName@gmail.com for the outgoing SMTP connection to Gmail's SMTP server via Exim4
• Your Exim4 relays local SMTP connections coming with the mail envelope address: YOUR-USER-NAME@localhost and YOUR-USER-NAME@localhost.localdomain
• Your account name for SMTP at Gmail is SMTPAccountName@gmail.com
• Your password for SMTP at Gmail is y0uRpaSsw0RD
   

# dpkg-reconfigure exim4-config

• Choose "mail sent by smarthost; received via SMTP or fetchmail"
• Set to "localhost" for "System mail name:".
• Set to "127.0.0.1" for "IP-addresses to listen on for incoming SMTP connections" to refuse external connections.
• Leave as empty for "Other destinations for which mail is accepted:".
• Leave as empty for "Machines to relay mail for:".
• Set to "smtp.gmail.com::587" for "IP address or host name of the outgoing smarthost:".
• Choose "NO" for "Hide local mail name in outgoing mail?".
• Choose "NO" for "Keep number of DNS-queries minimal (Dial-on-Demand)?".
• Choose "mbox format in /var/mail/" for "Delivery method for local mail".
• Choose "YES" for "Split configuration into small files?".

vi /etc/exim4/passwd.client

add the following lines:

*.google.com:SMTPAccountName@gmail.com:y0uRpaSsw0RD

# chown root:Debian-exim /etc/exim4/passwd.client # chmod 640 /etc/exim4/passwd.client

Edit your aliases file

# newaliases

# update-exim4.conf
# invoke-rc.d exim4 restart
# exim4 -qff

 tada

mostly grepped from here