Final answer:
The item 'New Policy on Secure Messaging' does not serve as a functional heading for an informal report because it is too specific and doesn't encapsulate a section like the other options.
Step-by-step explanation:
The item that is not a functional heading for an informal report among the options provided is d) New Policy on Secure Messaging. Functional headings in a report should be broad, capturing the essence of the section. Recommendations, Findings, and Problems are typical functional headings that summarize the content of the respective sections in an informal report. New Policy on Secure Messaging is too specific and sounds like a title of a particular policy document rather than a section within an informal report.