Create a Contact Group (formerly Distribution List)
A Distribution List (or Contact Group) is a collection of people you want to send email to at the same time.
Be careful not to create Office 365 groups(the bottom option on the last picture), which are a space for sharing conversations, documents, and a calendar with others. Office 365 groups are publicly displayed to all BYUI users where as Contact Groups are only seen by yourself.
Creating a Contact Group in Outlook:
If you create Contact Groups on a Macintosh computer they'll only be available on the computer they were created on. For Macintosh users who want to create groups that will synchronize with their mailbox please use OWA at http://outlook.office365.com/.
Creating a contact group in Outlook Web Access(email tab):