Because newsletter templates are available in all variety of lengths and sizes, there is really no limit to the content that you could potentially write. Keep in mind, however, that you should probably keep down your word count to a level that people are comfortable reading. While you may think everything that you are spouting off is fascinating, it's helpful to first sit down and make an outline of what you want your main message to be, or what the major news is that you are trying to share.
The Nameplate and Masthead _ You must have a nameplate including the name of your publication and the date it is published. You should have a masthead too. Both nameplate and masthead are necessary. Your masthead lets people know the name of the author if your newsletter is personal or it says contact information if it's a company newsletter.