gistfile1.rb

class ActionMailer::Base
  # We're using the SendGrid SMTP API to send emails to a large distribution
  # list.  During testing, we want to validate that each recipient received a
  # copy of the email.  Do that by looking for emails sent to a distribution
  # list and creating multiple copies, one for each recipient.
  def perform_delivery_test(mail)
    mail.ready_to_send # All duplicates must have same message id
    smtpapi = JSON.parse(mail["X-SMTPAPI"].to_s) if mail["X-SMTPAPI"]
    if smtpapi && smtpapi["to"]
      mail.delete "X-SMTPAPI"
      smtpapi["to"].each do |to|
        clone = TMail::Mail.parse(mail.to_s)
        clone["Delivered-To"] = to
        perform_delivery_test clone
      end
    else
      deliveries << mail
    end
  end
end