This article explains how to add members to a distribution list in Outlook 2019, Outlook 2016, Outlook 2013, Outlook.com, and Outlook for Microsoft 365.
How to change your Office 365 distribution list from Outlook
To add members to a distribution list (also called a contact group) in Outlook, follow these steps:
Open the Outlook desktop app and select the Home tab. Then select Address Book.
Select the distribution list in the Address Book window.
