a direction to any postmaster at the office at which registered or certified letters or other letters or mail arrive, addressed to the defendant or his representative, to return the registered or certified letters or other letters or mail to the sender appropriately marked as being in response to mail in violation of
section 3010 of this title, after the defendant, or his representative, has been notified and given reasonable opportunity to examine such letters or mail and to obtain delivery of mail which is clearly not connected with activity alleged to be in violation of
section 3010 of this title.