29 C.F.R. § 70.21 : Labor — OFFICE OF THE SECRETARY OF LABOR — PRODUCTION OR DISCLOSURE OF INFORMATION OR MATERIALS — PROCEDURES FOR DISCLOSURE OF RECORDS UNDER THE FREEDOM OF INFORMATION ACT — Responses to requests

(a) In general. Components should, to the extent practicable, communicate with requesters using the method that is most likely to increase the speed and efficiency of the communication, including by electronic means, such as by email.
(b) Acknowledgements of requests. A component will acknowledge each new request and assign it an individualized tracking number. Components will include in the acknowledgment a brief description of the records sought to allow the requesters to more easily keep track of their requests.
(c) Granting a request. After a component makes a determination to grant a request in full or in part, the component will notify the requester in writing. The component will provide the record in the form or format requested if the record is readily reproducible in that form or format, provided the requester has agreed to pay and/or has paid any fees required by subpart C of this part. The component will determine on a case-by-case basis what constitutes a readily reproducible format. Each component should make reasonable efforts to maintain its records in commonly reproducible forms or formats. The component must notify the requester of the right to seek assistance from the Department's FOIA Public Liaison.
(d) Adverse determinations of requests. A component making an adverse determination denying a request in any respect must notify the requester in writing. Adverse determinations, or denials of requests, include decisions that: The requested record is exempt, in whole or in part, from release pursuant to one or more exemptions under the FOIA, 5 U.S.C. 552; the request does not reasonably describe the records sought; the information requested is not a record subject to the FOIA; the requested record does not exist, cannot be located, or has been destroyed; or the requested record is not readily producible in the form or format sought by the requester. Adverse determinations also include denials involving fees or fee waiver matters or denials for requests for expedited processing.
(e) Content of the denial. The denial notice must be signed by the component agency head or a designee and will include:
(1) The name and title or position of the person responsible for the denial;
(2) A brief statement of the reason or reasons for the denial, including any FOIA exemption or exemptions applied or procedural reasons relied upon by the component in denying the request;
(3) An estimate of the volume of records or information withheld, in number of pages or in some other reasonable form of estimation. This estimate does not need to be provided if the volume is otherwise indicated through deletions on records disclosed in part, or if providing an estimate would harm an interest protected by the exemption under which the deletion was made;
(4) A statement that the denial may be appealed as described under Sec. 70.22; and
(5) A statement notifying the requester of the right to seek dispute resolution services from the Department's FOIA Public Liaison or the Office of Government Information Services (within the National Archives and Records Administration). Engaging in dispute resolution services provided by OGIS is a voluntary process. If the Department agrees to participate in the mediation services provided by OGIS, it will actively engage as a partner to the process in an attempt to resolve the dispute.
(f) Markings on released documents. Markings on released documents must be clearly visible to the requester. Records disclosed in part shall be marked to show the amount of information deleted and the exemption(s) under which the deletion was made unless doing so would harm an interest protected by an applicable exemption. The location of the information deleted shall also be indicated on the records, if technically feasible.

29 C.F.R. § 70.21

82 FR 7671, 1/23/2017