Similarly, the presence of an email address does not necessarily mean that the person checks their email regularly. This year's effort, as an initial effort, may accidentally omit some email addresses. Also, some email addresses may cease to be current, even though they remain in the Directory until the Directory is published again. So attempts to email to such an individual may fail. An individual's email address can be located on the computer system they use by using the appropriate locator comands.
Email is a relatively new communication option.
Unless you are relatively sure that the person involved either does or does not use email, a contact by another means is useful in establishing if email is a useful communications option with a particular person.