def preview_to(recipient)
      @newsletter = build_newsletter
      mail = build_mail
      mail.to = recipient.email
      replace_and_send_mail_safely(mail, recipient)
    end
def preview_to(recipient)
      @newsletter = build_newsletter
      mail = build_mail
      mail.to = recipient.email
      replace_and_send_mail_safely(mail, recipient)
    end
Send a preview email