Microsoft 365 Email Collaboration: Shared Mailboxes vs Distribution Lists vs Microsoft 365 Groups

Microsoft 365 offers several ways for people to collaborate around email, calendars, files, and conversations. The right choice depends on whether you need a simple email address, a shared inbox, a project workspace, a Teams-connected collaboration hub, or a legacy Exchange folder structure.

What changed since the old “Groups in Outlook” model?

The modern term is Microsoft 365 Groups. A Microsoft 365 Group is the identity and membership service behind many collaboration experiences in Microsoft 365, including Outlook groups, Microsoft Teams, SharePoint team sites, Planner, and group calendars.

A Microsoft 365 Group does not store files in OneDrive for Business. Group files are stored in a SharePoint Online team site document library. OneDrive is primarily for individual user files and ad hoc sharing, while SharePoint and Teams are better for team-owned content.

For most organizations in 2026, the decision is no longer only “distribution list or shared mailbox?” The better question is: Do users need email distribution, shared mailbox handling, real collaboration, Teams chat, structured document management, or a legacy Exchange folder?

Quick comparison: which Microsoft 365 collaboration option should you use?

Option	Best for	Mail behavior	Calendar	Files	Teams integration	Typical recommendation
Microsoft 365 Group	Team or project collaboration across Outlook, SharePoint, Planner, and Microsoft 365 apps	Group conversation mailbox; members can follow conversations in their inbox	Yes	SharePoint team site	Can be connected to a Team	Use for collaborative groups that need shared files, calendar, and workspace services.
Microsoft Teams team/channel	Active teamwork, chat, meetings, files, apps, and project communication	Email can be sent to channels if enabled; not a replacement for a shared support inbox	Meetings/calendar integration	SharePoint-backed files	Native	Use for day-to-day collaboration, projects, departments, and cross-functional work.
Shared mailbox	Role-based inbound mail such as info@, billing@, HR@, or support@	Mail stays in the shared mailbox; delegated users read and respond	Yes	No native document workspace	No native Teams workspace	Use when several people manage one business email identity.
Distribution list / distribution group	Sending the same email to multiple recipients	Message is delivered to each member’s personal mailbox	No	No	No	Use for simple announcements or routing mail to a group without collaboration features.
Dynamic distribution group	Emailing a changing audience based on attributes	Recipients are calculated by filters, such as department or location	No	No	No	Use for large or frequently changing recipient lists when attributes are well maintained.
Mail-enabled security group	Email distribution plus permission assignment	Can receive email and be used for access control	No	No	No	Use carefully for scenarios that need both email and permissions.
SharePoint Online site	Structured document management, intranet content, records, and knowledge sharing	Not primarily email-based	Optional via group-connected site	Yes	Can be connected through Teams	Use for document libraries, metadata, permissions, pages, and long-term content management.
Public folder	Legacy shared Exchange folder structures	Mail can be delivered to mail-enabled public folders	Possible	Limited and legacy-style	No	Keep for supported legacy scenarios; avoid for new collaboration designs unless there is a specific requirement.

Use a Microsoft 365 Group when you need a collaboration workspace

A Microsoft 365 Group gives a team a shared identity and membership list across Microsoft 365 services. Depending on how it is created and configured, it can provide:

• A group mailbox and group conversations in Outlook
• A shared calendar
• A SharePoint Online team site and document library
• A Planner plan
• A OneNote notebook
• Optional Microsoft Teams integration
• Guest access, if allowed by your organization’s policies

Use a Microsoft 365 Group when users need more than email distribution. It is a good fit for departments, projects, committees, and recurring business processes where people need to collaborate on messages, files, meetings, and tasks.

For active collaboration, many organizations create a Team in Microsoft Teams, which uses Microsoft 365 Groups and SharePoint behind the scenes. Teams then becomes the front-end for chat, meetings, channels, apps, and files.

Use a shared mailbox for role-based inbound email

A shared mailbox is best when multiple users need to monitor and respond from a common address, such as:

• info@company.com
• sales@company.com
• billing@company.com
• hr@company.com
• support@company.com

Shared mailboxes support delegated access. Administrators can grant users Full Access, Send As, or Send on Behalf permissions. These permissions are not the same:

• Full Access lets a user open and manage the mailbox.
• Send As makes replies appear as if they came directly from the shared mailbox address.
• Send on Behalf shows that the user sent the message on behalf of the shared mailbox.

Do not share passwords for shared mailboxes. In a secure Microsoft 365 configuration, users sign in with their own accounts, ideally protected by multifactor authentication and Conditional Access, and access the shared mailbox through delegation.

Licensing note: shared mailboxes generally do not require a separate license if they are within Microsoft’s unlicensed shared mailbox limits and users do not sign in to them directly. A license is typically required for scenarios such as larger mailbox size requirements, archive mailbox use, or certain compliance features such as Litigation Hold. Licensing can vary by subscription and feature set, especially under Microsoft’s current NCE subscription model, so it is worth validating requirements before deploying at scale.

Use a distribution list for simple email distribution

A distribution list or distribution group sends email to multiple recipients. It is simple, familiar, and still useful when the requirement is only to deliver a message to a group of people.

Use distribution lists for:

• Company announcements
• Department-wide notifications
• Emailing a group that does not need a shared mailbox, files, calendar, or Teams workspace
• Simple internal communication lists

Use dynamic distribution groups when membership should be calculated automatically from recipient attributes, such as office, department, region, or employment type. This works well only if directory data is accurate and consistently maintained.

Distribution lists are not ideal for collaboration because they do not provide a shared workspace, shared files, persistent group conversations, Planner tasks, or Teams channels. If the group needs to work together, consider a Microsoft 365 Group or Team instead.

Use SharePoint or Teams for files—not public folders

Public folders are still supported in Exchange Online, but they are best viewed as a legacy or specialized Exchange feature. They can be useful when an organization has established workflows based on hierarchical mail folders, mail-enabled public folders, or legacy Outlook access patterns.

For new deployments, use modern collaboration platforms instead:

• Use SharePoint Online for document libraries, permissions, metadata, version history, pages, records, and structured content management.
• Use Microsoft Teams when users need chat, meetings, channels, apps, and shared files in one workspace.
• Use a shared mailbox when the main need is a team-managed email inbox.

Avoid using public folders as a new document-sharing platform. They do not provide the same modern file collaboration, governance, coauthoring, search, or user experience as SharePoint and Teams.

Current client experience

Modern Microsoft 365 collaboration is designed for current clients and web experiences, including:

• Outlook on the web
• New Outlook for Windows
• Classic Outlook for Windows with supported Microsoft 365 Apps versions
• Outlook for Mac
• Outlook mobile for iOS and Android
• Microsoft Teams desktop, web, and mobile apps
• SharePoint Online and OneDrive web/mobile experiences

Older Outlook versions such as Outlook 2007, 2010, and 2013 are no longer appropriate planning targets for Microsoft 365. Organizations should standardize on supported Microsoft 365 Apps and modern authentication.

Governance matters: avoid Microsoft 365 sprawl

Collaboration tools are easy to create, which is useful—but without governance, tenants can quickly accumulate abandoned groups, duplicate Teams, unmanaged guests, and inconsistent permissions.

Recommended governance controls include:

• Define naming conventions for Teams, Microsoft 365 Groups, shared mailboxes, and distribution lists.
• Assign at least two owners for Microsoft 365 Groups and Teams where possible.
• Control who can create Microsoft 365 Groups if your organization requires centralized governance.
• Use Microsoft Entra ID and Microsoft 365 admin controls to manage membership, ownership, and guest access.
• Review external sharing settings for Teams, SharePoint, and Microsoft 365 Groups.
• Use sensitivity labels where appropriate to classify groups, sites, and Teams.
• Apply retention policies, eDiscovery, and Microsoft Purview controls based on business and compliance requirements.
• Review inactive groups, Teams, distribution lists, and shared mailboxes on a regular lifecycle schedule.
• Apply least-privilege access rather than granting broad permissions by default.

Good governance does not mean blocking collaboration. It means giving users clear, secure options that match business needs.

Migration guidance for older collaboration setups

Many organizations still have older distribution lists and public folders that were created before Teams and modern Microsoft 365 Groups became common. Not everything needs to be migrated, but each item should have a purpose.

A practical migration approach is:

1. Inventory distribution lists, dynamic distribution groups, shared mailboxes, mail-enabled security groups, and public folders.
2. Identify owners and confirm whether each object is still needed.
3. Classify the use case: announcement list, shared inbox, project workspace, document repository, or legacy archive.
4. Migrate where appropriate:
   • Distribution list to Microsoft 365 Group or Team if collaboration is needed.
   • Public folder documents to SharePoint if users need modern file management.
   • Public folder mail workflows to shared mailboxes or Microsoft 365 Groups when suitable.
   • Legacy departmental collaboration to Teams and SharePoint.
5. Retire stale objects after confirming retention and compliance requirements.

The goal is not to replace every older tool automatically. The goal is to align each collaboration pattern with the right Microsoft 365 service.

Practical decision guide

Use this simplified rule set:

• Need one shared business email identity? Use a shared mailbox.
• Need to send announcements to many people? Use a distribution list or dynamic distribution group.
• Need a team workspace with email, calendar, files, and tasks? Use a Microsoft 365 Group.
• Need chat, meetings, channels, apps, and working files? Use Microsoft Teams.
• Need structured document management or intranet content? Use SharePoint Online.
• Need to keep an existing Exchange folder hierarchy for a specific legacy workflow? Keep or modernize public folders after review.

When in doubt, design around the work users are doing—not just the address they want to create.

Key takeaways

• Microsoft 365 Groups replaced the older “Groups in Outlook” framing and now underpin Outlook groups, Teams, SharePoint team sites, Planner, and other collaboration experiences.
• Use shared mailboxes for role-based inbound email such as info@, sales@, billing@, or support@.
• Use distribution lists for simple email distribution, not for full collaboration.
• Use Teams and SharePoint for modern teamwork and document collaboration; avoid public folders for new file-sharing scenarios unless there is a specific legacy requirement.
• Plan governance up front: naming, ownership, guest access, lifecycle reviews, sensitivity labels, retention, and least-privilege permissions are essential.

Need help choosing or cleaning up your Microsoft 365 collaboration model? IT Partner can review your Exchange Online, Teams, SharePoint, Microsoft Entra ID, and Microsoft 365 governance settings and help design a secure, manageable structure for shared mailboxes, groups, Teams, and distribution lists.