Python/netrc

The netrc module can be a nice way to store credentials securely:

import netrc

HOST = 'smtp.gmail.com'
secrets = netrc.netrc()
username, account, password = secrets.authenticators( HOST )

Then in your ~/.netrc file include the following:

machine smtp.gmail.com
        username your_username
        password your_password

Make sure the mode is safe on the .netrc file, and you're set! You can easily call the netrc settings from any python script.