A contact group, formerly called a distribution list, allows you to send an email to multiple people at once by typing a single name in the "To" field. The exact steps differ slightly between the "classic" and "new" versions of Outlook. 

In classic Outlook

1. Click the People icon on the navigation bar at the bottom of the screen.
2. On the Home tab, click New Contact Group.
3. In the new window, type a name for your group in the Name box.
4. Click Add Members and select where you want to add contacts from:
   • From Outlook Contacts: Select names from your personal contact list. To select multiple contacts, hold down the Ctrl key as you click each one.
   • From Address Book: Choose from your organization's global address list.
   • New E-mail Contact: Enter a new email address that isn't saved in your contacts.
5. After adding all the members, click OK.
6. Click Save & Close. 

In new Outlook for Windows

1. Click the People icon on the side panel.
2. Select Your contact lists.
3. On the toolbar, select the arrow next to New contact and choose New contact list.
4. Enter a name for your list and then add names or email addresses.
5. Click Create. 

In Outlook on the web (Outlook.com)

1. Go to the People page.
2. On the toolbar, select the arrow next to New contact and then select New contact list.
3. Enter a name for the list and add names or email addresses.
4. Click Create. 

To use your contact group

1. Create a new email message.
2. In the "To" field, start typing the name of your contact group. Outlook will suggest the group name.
3. Click the name of the group to add it to your email. You can click the "+" symbol to expand the list and see all the individual members.