Email relay configuration on your Mac OS X

2 minutes to read

There are times when you wish your development stack could send some emails. Well, there is an easy way to do that on the Mac OS X (this was tested from the SL, Lion and Mountain Lion, but it should work in other versions, as also with Unix-like systems that, of course, have Postfix installed).

Start by adding these settings to your /etc/postfix/ file:

relayhost = []:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options =
smtp_sasl_local_domain =
broken_sasl_auth_clients = yes
smtpd_pw_server_security_options = noanonymous

I normally set this settings at the end of the file so I don't have to search it when I need to make a change. Also, I normally wrap it with something like # me@mymachine comment, so it's easy to search for whatever configurations I made on the original file. This doesn't mean you don't need to backup your settings file, it only means that it will be easier than to make diff or whatever.

If you use a gmail account, you can replace the line:

relayhost = []:587


relayhost =

and if you're using your development machine just replace:

smtp_sasl_local_domain =


smtp_sasl_local_domain = localhost

or remove it, since it isn't necessary for localhost.

If your relaying mail server needs authentication, the next step you'll need to do is to create the file /etc/postfix/sasl_passwd and add the following lines:

[]:587 username:password

So, for the gmail account it goes something like:

Don't forget to replace username with your actual username and password with your password! :)

Now you need to create the /etc/postfix/sasl_passwd.db file from the /etc/postfix/sasl_passwd one and keep them safe:

sudo postmap hash:/etc/postfix/sasl_passwd
sudo chown root:wheel /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
sudo chmod 600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db

There you go, all set. You should now be ready to send out some emails. Try it by sending an email from the terminal using:

echo 'Email is now working! :)' | mail -s 'Test Email' <>

If something goes wrong, you can monitor the log file at /var/log/mail.log in order to see what is happening, and use the mailq program to see the state of the mail queue.

If you have the 2-step verification on your google account, then you'll have to generate an application-specific password (I think you should know where is it).