(a) In representing a client, an attorney shall not use means that have no substantial purpose other than to embarrass, delay, or burden a third person, or use methods of obtaining evidence that the attorney knows violate the legal rights of such a person.
(b) An attorney who receives a document, electronically stored information, or other property relating to the representation of the attorney's client and knows or reasonably should know that the document, electronically stored information, or other property was inadvertently sent shall promptly notify the sender.