Configure Postfix for Gmail SMTP in Mac OSX Mavericks

Taken from Using MacOSX Lion command line mail with Gmail as SMTP

Edit file /etc/postfix/main.cf

sudo vim /etc/postfix/main.cf

and add in the following below the commented out relayhosts :-

myhostname = smtp.gmail.com

.
.
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# SASL SUPPORT FOR SERVERS
#
# The following options set parameters needed by Postfix to enable
# Cyrus-SASL support for authentication of mail servers.
#
relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_use_tls = yes

Create a sasl_passwd if one doesn't exist

sudo vim /etc/postfix/sasl_passwd

and enter in the following:-

[smtp.gmail.com]:587 username@gmail.com:password

Run the following commands

sudo chmod 600 /etc/postfix/sasl_passwd
sudo postmap /etc/postfix/sasl_passwd
sudo launchctl stop org.postfix.master
sudo launchctl start org.postfix.master

test by sending the contents of a directory to an email address with the following:

tree /var/www/somefolder | mail -s "contents" your@yourdomain.com

If you receive the following error:

send-mail: fatal: chdir /Library/Server/Mail/Data/spool: No such file or directory

you can do the following:

sudo mkdir -p /Library/Server/Mail/Data/spool
sudo /usr/sbin/postfix set-permissions
sudo /usr/sbin/postfix start

as per this question.

NB: If things aint sending / receiving, and you're getting notices, check that the mail servers you're using are actually working!

NOTE: A crappy way to get around Google's

Someone just tried to sign in to your Google Account [youremail]@gmail.com from an app that doesn't meet modern security standards.

is to enable less secure apps on your account: https://www.google.com/settings/security/lesssecureapps. Do this at your own discretion.