AD Mail enabled security group explained

You can use mail-enabled security groups to distribute messages as well as grant access permissions to resources in Exchange and Active Directory. You can create, modify, and remove mail-enabled security groups in the Exchange admin center (EAC) or in the Exchange Management Shell.

Distribution groups A distribution group is a mail-enabled Active Directory distribution group object that can be used only to distribute messages to a group of recipients. Mail-enabled security group A mail-enabled security group is an Active Directory universal security group object that can be used to assign access permissions to resources in Active Directory and can also be used to distribute messages.

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