Long lines can be hard to read in emails, as such it is considered proper email etiquette to break the lines of your messages to somewhere between 65 and 90 characters. When you wrap long lines of text, the Outlook email client automatically breaks sentences away from the current line to start on a new line. This shortens the length of all outgoing emails and is similar to narrowing the margins of the writing space. Outlook has a useful setting to set the line wrap to whatever number is needed.