Newsletters in the Communication System of Science 
Newsletters play several important roles in the scientific community because they can be used to convey information (e.g., administrative information) that is not appropriate for more formal genres (e.g., journals) and because they can be a more timely form of communication than other media, such as books.
O'Hara, Frederick M., Jr. STC Proceedings (1995). Articles>Scientific Communication>Publishing>Newsletters