A mail cover is an investigative technique that involves law enforcement review of infor-
mation that can be observed on the outside of correspondence conveyed in the U.S.
mail. Mail covers are conducted through the authority of the local postmaster. A mail
cover does not involve opening mail, nor does it permit the review of materials inside
an envelope. (It should be noted that certain chemicals will allow a person to read a let-
ter without opening the envelope in which it is contained. Authority for a mail cover
does not permit the use of these chemicals or any other means that might exist that
would permit the reading of a communication contained inside a sealed envelope.) Mail
cover authority does not permit an investigator to open a person’s mailbox in order to
study the envelopes containing his mail. Mail covers are usually conducted by postal
employees, with results given to the requesting law enforcement agency.