O365 Distribution List vs groups vs Sharedmailbox

We often get asked this question hence adding it as a blog for our new and existing customer to understand the concept.

This blog talks about how and when to use the 3 mailbox options. In Microsoft 365 (O365), Distribution Lists (DLs), Groups, and Shared Mailboxes serve different purposes, even though they all enable collaboration and email communication. Below is a comparison to help clarify their differences and use cases:

1. Distribution List (DL)

• Purpose: Used for sending emails to multiple recipients at once.
• Email Storage: No mailbox storage; emails are forwarded to members.
• Access Control: Members cannot access a shared mailbox; they only receive emails in their own inbox.
• Reply Handling: Replies go from individual members, not a shared mailbox.
• Best Use Case: Broadcasting emails to a group (e.g., newsletters, announcements).
• Admin Management: Managed via Exchange Admin Center (EAC) or Microsoft 365 Admin Center.
• Licensing Requirement: No license required.

✅ Pros:

• Simple to set up and manage.
• Efficient for large email broadcasts.
• No additional licensing required.

❌ Cons:

• No central storage of emails.
• Members don’t have a shared mailbox or collaboration tools.

2. Microsoft 365 Group (M365 Group)

• Purpose: Provides a collaboration workspace with a shared mailbox, SharePoint site, Teams, Planner, and other Microsoft 365 services.
• Email Storage: Yes, it includes a shared mailbox.
• Access Control: Members can access the shared mailbox and reply as the group.
• Reply Handling: Replies can come from the group mailbox.
• Best Use Case: Collaborative teams that need a shared workspace for emails, files, and discussions.
• Admin Management: Managed via Microsoft 365 Admin Center or Azure AD.
• Licensing Requirement: No license required unless using premium features.

✅ Pros:

• Integrates with Microsoft Teams, SharePoint, Planner, and OneDrive.
• Supports collaborative tools beyond just email.
• Members can reply from the shared mailbox.

❌ Cons:

• More complex than a simple distribution list.
• Can become cluttered if not managed properly.

🔹 Types of M365 Groups:

• Outlook-based Groups: Used primarily for email collaboration.
• Teams-based Groups: Used for chat and collaboration with Microsoft Teams.

3. Shared Mailbox

• Purpose: A centralized mailbox that multiple users can access to send and receive emails.
• Email Storage: Yes, has its own mailbox storage.
• Access Control: Users must be assigned explicit permissions (Full Access, Send As, or Send on Behalf).
• Reply Handling: Users can send emails as the shared mailbox (e.g., support@company.com).
• Best Use Case: Managing customer service emails, team inboxes, or role-based accounts.
• Admin Management: Managed via Exchange Admin Center or Microsoft 365 Admin Center.
• Licensing Requirement: No license required if under 50GB, but users need an Exchange Online license.

✅ Pros:

• Allows multiple users to access and respond to emails as a team.
• Emails are stored centrally and accessible to all authorized users.
• Supports Send As and Send on Behalf permissions.

❌ Cons:

• Cannot be used for scheduling meetings (no calendar invites).
• Requires explicit permissions management.
• Cannot be accessed directly via Outlook mobile app (must be added via delegation).

Key Differences & When to Use Each

Which One Should You Choose?

• Use a Distribution List if you just need to send emails to a group without storing them centrally.
• Use a Microsoft 365 Group if you need collaboration features beyond email (Teams, SharePoint, Planner).
• Use a Shared Mailbox if you need multiple users to manage emails from a central address (e.g., support@company.com).