An email distribution list in Outlook 2016, 2013 and 2010 can be creating using the New Contact Group option available as part of the Contacts Home option. To create a new email distribution list, go to the navigation pane and select Contacts.
Now navigate to the Contacts Home menu and click the New Contact Group menu option
In the following New Contact Group window, provide a name to the distribution list e.g. Tech Support and to add members to this list click the Add Members menu option
You can choose from you want to add the members from such as Outlook Contacts, From Address Book or specify a New E-mail Contact.
After adding the Contact click the Save & Close menu. This would save the newly created Contact Group.
Now this distribution list will be available as part of of your mailing list.