This form of letter is usually requested by businesses and contractors as a formal document acknowledging performance of a service or delivery of a letter or materials.
The letter forms part of the legal record of transactions between them and your business.
Requests for letters of acknowledgement of receipt are quite common, and are often issued in lieu of other forms of commercial receipt, or as interim receipts, and that's their basic legal status.
Email also often includes a 'receipt requested' function. In both cases, the letter of acknowledgement simply meets a need for the party requesting it.
Note: The only good reason not to issue a letter of acknowledgement is if you have some objection to the content requested.
Do NOT issue any acknowledgement, if there are problems with the materials or other matters concerned.
Use a separate letter in response, dealing with the issues involved.Example:
Acknowledgement of receipt of (brief description)
I refer to your letter / email of (date) and as requested acknowledge receipt of (description of materials or services specifically as requested) on (date).