What is a Microsoft 365 Group?
If you administer Microsoft 365 for a small business, you have probably encountered “groups” in more than one context — as a way to manage email distribution, as a way to control access to files, and as the invisible plumbing behind every Microsoft Teams team. Understanding what a Microsoft 365 Group actually is, and how it differs from other group types, helps you make better decisions about collaboration, access, and long-term cleanup.
According to Microsoft, a Microsoft 365 Group is designed for collaboration between people inside and outside your company. When a Microsoft 365 Group is created, members get a shared mailbox, calendar, and workspace for conversations and files, along with a connection to SharePoint and Planner. Microsoft 365 Groups can also be connected to Microsoft Teams or Viva Engage.
This is different from simply sending an email to a distribution list or granting access through a security group. A Microsoft 365 Group bundles several services together under one membership list, so adding or removing a person from the group can affect their access to several tools at once.
How Microsoft 365 Groups compare to other group types
Microsoft 365 admin center supports several group types, and it is easy to confuse them. Based on Microsoft’s own comparison, here is how they differ:
- Microsoft 365 Groups — used for collaboration; include a shared mailbox, calendar, files, and SharePoint site; can connect to Teams; support both mail and dynamic membership.
- Distribution groups — used only for sending email notifications to a set list of people; do not support dynamic membership.
- Security groups — used to grant access to resources like SharePoint sites; not mail-enabled by default; support dynamic membership; can contain users or devices.
- Mail-enabled security groups — function like security groups but can also receive email; cannot use dynamic membership and cannot contain devices.
- Shared mailboxes — used when multiple people need access to a single mailbox, such as a support inbox; cannot be migrated into a Microsoft 365 Group.
- Dynamic distribution groups — membership is calculated at the moment an email is sent, based on attributes such as department or location.
A few structural facts are worth remembering for practical planning:
- Microsoft 365 Groups cannot be members of distribution groups or security groups.
- Distribution groups can be added to a Microsoft Teams team, but according to Microsoft’s documentation, only the members are added — the distribution group itself is not layered into Teams the way a Microsoft 365 Group is.
- Security groups and mail-enabled security groups can also be added to a team. Microsoft’s documentation confirms this is possible but does not specify whether the same “members only” behavior applies to these group types, so admins should not assume it works identically to distribution groups.
For an SMB admin, this means Microsoft 365 Groups are the right choice when you want a genuinely shared workspace (mailbox, calendar, files, and potentially a Teams team), while security groups or mail-enabled security groups are better suited to permission management or email-only scenarios.
How Microsoft 365 Groups relate to Teams, SharePoint, and Outlook
Microsoft Teams
Microsoft Teams is built on Microsoft 365 Groups. According to Microsoft’s documentation on teams and channels, when membership in the underlying Microsoft 365 Group changes, that change syncs to the team. In practice, this means that when you create a team in Microsoft Teams, Microsoft is also creating (or connecting to) a Microsoft 365 Group behind the scenes, and managing group membership is effectively how you manage who is part of that team.
Microsoft also distinguishes between two team access types:
- Private teams — restricted to members approved by the team owner(s); commonly used for project or departmental teams.
- Public teams — open to anyone in the organization, who can join directly; described by Microsoft as a good default setting for smaller organizations.
For a small business, this distinction matters operationally. A public team lowers the friction for employees to find and join relevant teams, while a private team gives an owner more control over who has access to the group’s shared resources.
SharePoint
Microsoft 365 Groups can be added to one of three SharePoint groups — Owners, Members, or Visitors — to grant people permissions to a SharePoint site. This means the same group that governs a shared mailbox and Teams membership can also determine who can view or edit files on the associated SharePoint site, reinforcing the “one membership list, many services” model.
Outlook
Members of a Microsoft 365 Group get access to a group email address and a shared mailbox and calendar. Microsoft notes that group members can access Microsoft 365 Groups through mobile apps such as Outlook for iOS and Outlook for Android. Administrators can also enable members to send as or send on behalf of the group’s email address, and can allow external senders to email the group if that is appropriate for the organization.
One detail worth understanding for support purposes: if a member deletes a group email from their personal inbox, it is not deleted from the group’s shared mailbox, and vice versa. This can prevent confusion when a user reports a “missing” group email that is still visible to other members.
Ownership, membership, and lifecycle: what SMB admins should know
Roles: owners vs. members
Based on Microsoft’s guidance for the My Groups portal, the two key roles are:
- Group members can view group details and leave the group (except for security groups, which behave differently).
- Group owners can view details, create new groups, add or remove members, renew expiring groups, and delete the group.
Because ownership carries meaningful lifecycle authority — including the ability to delete a group — it is worth being deliberate about who is assigned as an owner, particularly for groups tied to a Teams team or a shared SharePoint site.
Creating a Microsoft 365 Group
Depending on organizational policy, users may be able to create a Microsoft 365 Group themselves through the Groups page in the My Groups portal, or this capability may be restricted by an administrator. When creating a group, Microsoft’s guidance describes several configurable settings, including:
- Group name and email alias
- Group description and sensitivity label
- Group visibility (Public — anyone in the organization can join — or Private — membership requires approval)
- Whether to send a welcome email to new members
- Whether members auto-follow group conversations
- Whether the group mailbox and calendar are visible in Outlook
- Authorized senders (if left blank, all members can send messages to the group)
- Whether the group is hidden from the global address list
- Whether security group functionality is enabled (Microsoft notes this cannot be disabled once turned on)
- Whether people outside the organization can email the group
Not all of these settings may be visible to every user, since availability can depend on organizational policy.
Renewing and deleting groups
Microsoft 365 Groups can expire, and if the organization allows it, an owner can renew a group to extend its expiration date.
When a Microsoft 365 Group is deleted, Microsoft retains it in a soft-deleted state for 30 days by default. During that period, the group can be restored, including associated resources such as its Exchange mailbox and calendar, SharePoint team site and files, Planner, and Teams. After the 30-day retention period, the group and its associated content are permanently deleted and can no longer be restored.
This still makes deletion a deliberate administrative action, particularly for groups that support active Teams or SharePoint workloads.
Joining existing groups
Users can also request to join an existing group through the Groups page. If the group requires owner approval, the requester may need to provide a business justification; if not, they are added immediately.
Practical recommendations for SMB administrators
The following are practical suggestions rather than documented Microsoft requirements, and they should be adapted to your organization’s own governance needs:
- Assign more than one owner to groups that support important shared resources (such as a departmental Teams team), so that lifecycle actions like renewal or deletion do not depend on a single person.
- Review group visibility settings (Public vs. Private) with an eye toward how sensitive the group’s content is, since visibility affects who can join or view the group.
- Periodically review group membership, especially for groups connected to Teams or SharePoint, since membership changes flow through to those connected services.
- Clarify internally which group type to use for a given need — a Microsoft 365 Group for collaborative work, a distribution group for simple email broadcasts, or a security group for access control — to avoid creating overlapping or redundant groups.
- Treat group deletion as a deliberate action, because deleting a Microsoft 365 Group also affects its connected services. Deleted groups can normally be restored during Microsoft’s 30-day soft-delete period, but after that the group and associated content are permanently removed.
Conclusion
Microsoft 365 Groups sit at the center of collaboration in Microsoft 365, quietly connecting Outlook, SharePoint, and Microsoft Teams through a single membership list. For SMB administrators, the practical takeaway is that managing a group’s membership and ownership is not a narrow administrative task — it directly shapes who can access a shared mailbox, a SharePoint site, and potentially an entire Teams team. Taking the time to understand ownership responsibilities, visibility settings, and the permanence of deletion will help your organization use Microsoft 365 Groups deliberately rather than accumulating groups that are hard to track or clean up later.