actionmailer + smtp + CFG

cfg-ex.rb

CFG = {
  test: {},
  prod: {},
  dev: {
    ...
    # smtp: { ... }
  }
}

cfg-prod.rb

CFG = {
  test: {},
  dev: {},
  prod: {
    # ...
    smtp: {
      address:              'smtp.gmail.com',
      port:                 587,
      authentication:       'plain',
      enable_starttls_auto: true,
      user_name:            'somebody@gmail.com',
      password:             '...',
    },
  }
}

production.rb

# Action mailer settings
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = CFG[:prod][:smtp]
config.action_mailer.perform_deliveries = true
config.action_mailer.raise_delivery_errors = true

# ActionMailer::Base.default :from => 'foo@example.com'