Difference Between Exchange Online Shared Mailboxes and User Mailboxes
Overview
Understanding the differences between an Exchange Shared Mailbox and a User Mailbox is essential for configuring Microsoft Exchange effectively.
Shared mailboxes are designed for team-based email management and do not require individual login credentials.
User mailboxes are assigned to individual users and require an Exchange Online license, though access can be shared through delegated permissions.
This guide outlines the key distinctions, including use cases, licensing, and permissions.
1. Exchange Shared Mailbox
Overview
An Exchange Shared Mailbox is a mailbox that multiple users can access to send and receive emails. It does not have its own login credentials and is commonly used for team-based email management, such as customer support or general inquiry accounts.
Key Characteristics
Shared Access – Multiple users can access the mailbox through assigned permissions instead of sharing login credentials.
No Login Required – Users access the shared mailbox using their own accounts with appropriate permissions (Full Access, Send As, or Send on Behalf).
Licensing – No license is required if the mailbox size is under 50GB. If it exceeds 50GB, an Exchange Online Plan 2 license is required.
Designed for Team Collaboration – Ideal for group-based communication, such as customer service or shared inboxes.
Email Sending – Emails sent from a shared mailbox appear as the shared mailbox’s address. Users must have “Send As” or “Send on Behalf” permissions to send emails on behalf of the mailbox.
Common Use Cases
Customer service or team-based email addresses such as support@example.com or info@example.com.
General inquiry mailboxes used by multiple team members.
2. User Mailbox Shared with Others
Overview
A User Mailbox is assigned to an individual user, but access can be shared with others through delegation (Full Access, Send As, or Send on Behalf). It is intended for personal use but can be shared for collaboration when necessary.
Key Characteristics
Individual Ownership – Each user mailbox is assigned to a specific person with their own login credentials.
Sharing via Permissions – Access to the mailbox is granted by delegating permissions to other users.
Requires License – Unlike shared mailboxes, user mailboxes always require an Exchange Online license.
Email Sending – Emails sent from a user mailbox show the original user’s email address unless “Send As” or “Send on Behalf” is configured.
Common Use Cases
Personal mailboxes where the user needs to delegate access to an assistant or team member.
Executive assistants who manage another user’s mailbox.
3. Key Differences Between Shared and User Mailboxes
Feature | Exchange Shared Mailbox | User Mailbox Shared with Others |
|---|---|---|
Ownership | No individual ownership; accessible by multiple users. | Owned by an individual user. |
Access | Accessed via permissions assigned to multiple users. | Accessed by delegating permissions to others. |
Licensing | No license required if under 50GB. License needed if over 50GB. | Requires an Exchange Online license. |
Login Credentials | No login credentials; accessed through users’ accounts. | Tied to the individual user’s login credentials. |
Email Sending | Emails sent from the shared mailbox’s address. | Emails sent from the individual user’s address or with “Send As” permissions. |
4. Licensing Considerations
Shared mailboxes under 50GB do not require a license.
Shared mailboxes over 50GB require an Exchange Online Plan 2 license.
All users accessing a shared mailbox must have an Exchange Online license.
User mailboxes always require an Exchange Online license.
Additional Resources
Microsoft Answers: Difference Between Shared Mailbox and User Mailbox
Emazzanti: Shared Mailbox vs Regular Mailbox in Microsoft Exchange
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