gmail-smtp.rb

# /config/environments/development.rb or /config/environments/production.rb

# Gmail configuration
config.action_mailer.raise_delivery_errors = true
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  address:              'smtp.gmail.com',
  port:                 587,
  domain:               'example.com',
  user_name:            ENV['EMAIL_USER'],
  password:             ENV['EMAIL_PASS'],
  authentication:       'plain',
  enable_starttls_auto: true
}