Custom delivery method to replace recipient on sendmail for a staging environment

sendmail_staging.rb

# lib/utils/sendmail_staging.rb

class SendmailStaging < ::Mail::Sendmail
  
  # mail object can be used to modify mail before we pass it
  # to sendmail
  def deliver!(mail)
    mail['to'] = '[email protected]' #replace recipient
    super(mail) #Let Sendmail do his work
  end
end

sendmail_staging_delivery_method.rb

# config/initializers/sendmail_staging_delivery_method.rb

# Register the custom delivery method:
ActionMailer::Base.add_delivery_method :sendmail_staging, SendmailStaging

staging.rb

# config/environment/staging.rb

Rails.application.configure do
  
  # ... other configs ...
  
  config.action_mailer.delivery_method = :sendmail_staging
  
  # ... other configs ...
  
end