A Distribution List (DL) is used to simplify the action of sending an email to multiple users. Each DL has a Name, email address, Manager and group of members.
Name: This is a friendly name that will appear in the Address List of your organisation. Common names are "All Users", "Sales Team", "Management Team".
Manager: A Manager is a mailbox user in your organisation who has the ability to change the membership of a DL from within the Outlook client or Outlook Web App.
Members: These are mailbox users or contacts from your Organisation that will receive emails sent to this DL either internally from the address list or externally to the DL's email address.