Answer:
External users will be able to access the message.
Explanation:
When dealing with the internal email system of an enterprise, it's possible to do a recall on the message. If someone on the internal list didn't open the message yet, it will simply be deleted from his queue and it will appear as is that email never existed.
For external users, once the email has been sent, it cannot be recalled... so they'll be able to access it no matter what, because that email exists on an external server on which you have no management control.
Answer:
A. OU
Explanation:
An organization unit (OU) is used to group objects that are related, having similar administrative and security requirements within a domain. It provides a way of classifying objects in a directory, such as differentiating between objects with the same name or managing and creating objects. An OU can be nested into another OU, thus it can be used to create a hierarchy within an organization.