In Windows Server 2016 enterprise network there are two types of groups.
Security and distribution.
When you create a group you choose the group type and school group types determines the capabilities
of the group.
Email applications mainly use distribution groups which are not security enabled security groups are
security enabled and you use them to assign permissions to various resources you can use.
Security groups and permission and trust in access control lists to control security for resource access.
You can use security groups as a means of distribution for email applications.
If you want to use a group to manage security it must be a security group.
Please know that the default group type for newly created groups is security because you can use security
groups for both resource access and email distribution.
Many organizations use only security groups.
However it is recommended that if you use a security group for email distribution only you should create
the group or the distribution group otherwise the group with a scientist security identifier seed and
the seed is added to the user security access token which can make the token unnecessarily large.
You can convert a security group to a distribution group at any time.
When you do this the group type attribute changes.
A security group that you have converted to a distribution group therefore loses all permissions assigned
to it even though the ACL still contains the seed.
If you convert a distribution group to a security group the reverse cures the group type attribute changes
and you can now assign permissions to resources to the group.
Consider that when you add a user to a security group the users access token which authenticates user
processes updates only when the users sign in.
Therefore if the user is currently signed in the user must sign out and then sign back in to update
his or her access token with any changed user or memberships.
Now the benefit of using distribution groups becomes more evident in large scale exchange server deployments
especially when you need to nest these distribution groups across the enterprise.