28 C.F.R. § 540.2
(a) General correspondence means incoming or outgoing correspondence other than special mail. General correspondence includes packages sent through the mail.
(b) Representatives of the news media means persons whose principal employment is to gather or report news for:
(c) Special mail means correspondence sent to the following: President and Vice President of the United States, the U.S. Department of Justice (including the Bureau of Prisons), U.S. Attorneys Offices, Surgeon General, U.S. Public Health Service, Secretary of the Army, Navy, or Air Force, U.S. Courts (including U.S. Probation Officers), Members of the U.S. Congress, Embassies and Consulates, Governors, State Attorneys General, Prosecuting Attorneys, Directors of State Departments of Corrections, State Parole Commissioners, State Legislators, State Courts, State Probation Officers, other Federal and State law enforcement offices, attorneys, and representatives of the news media.
Special mail also includes correspondence received from the following: President and Vice President of the United States, attorneys, Members of the U.S. Congress, Embassies and Consulates, the U.S. Department of Justice (excluding the Bureau of Prisons but including U.S. Attorneys), other Federal law enforcement officers, State Attorneys General, Prosecuting Attorneys, Governors, U.S. Courts (including U.S. Probation Officers), and State Courts. For incoming correspondence to be processed under the special mail procedures (see §§ 540.18-540.19), the sender must be adequately identified on the envelope, and the front of the envelope must be marked “Special Mail—Open only in the presence of the inmate”.