What is considered a "management letter" for a publicly traded company?

Question

Is it the SOX section 204 or 404 requirement or something else?

Answer 1

Under Sox 404, among other things, the auditor must form an opinion on the effectiveness of the internal control structure and whether deficiencies exist. All deficiencies must be reported in writing to management, in a "Management letter". All significant deficiencies and /or all material weaknesses must be reported in writing to the audit committee.