You may want to create announcements for upcoming department events, assignments, exams, etc. When you create an assignment, you have the option of sending the announcement out as an e-mail in addition to appearing on your course site.
Under Web Announcement Options, set your announcement's date restriction options and check the box next to Email Announcement if you want to also send the announcement via email.
If you select the Email Announcement option it will ignore any date restrictions on the announcement and sent the email immediately.
Under Course Link, select a location to link to, if you wish.
This will create a link to a tool or another content area in your course, not to your computer. If the course item is hidden from students, the announcement will not be visible until the item is available.