A newsletter is typically a short, periodic email that informs subscribers about new products, services, or events. However, some newsletters are also known as “e-letters,” “white papers,” or “info-letters.”
Some newsletter providers advocate that the term “newsletter” be reserved for those emails that are sent on a more regular basis (e.g., every other week), while others argue that the term can be used for any email that is shorter than a blog post.
Ultimately, it is up to the provider to decide which term they prefer.
The conclusion of this article is that a newsletter can be two words or three words, it just needs to be short and to the point.