If your business has a central email address (info@, support@, sales@, or accounts@) that more than one person needs to access and respond from, a shared mailbox in Microsoft 365 is almost certainly the right solution. Set up correctly, shared mailboxes are one of the most practical and cost-effective features in the Microsoft 365 toolkit. Set up poorly, they quickly become a source of missed emails, duplicated replies, and frustration.

Here’s a clear guide to what shared mailboxes are, how they work, how to create one, and the best practices that make the difference between a shared mailbox that works well and one that doesn’t.

 

 

 

What Is a Shared Mailbox?

 

A shared mailbox is a Microsoft 365 email account that multiple users can access to send and receive emails from a common address. Unlike a standard user mailbox, a shared mailbox doesn’t have its own username and password — team members access it using their own Microsoft 365 credentials, and it appears alongside their personal mailbox in Outlook.

This makes shared mailboxes ideal for business functions that require a team response; customer enquiries, technical support, billing questions, or general company communications. Everyone authorised can see incoming messages, reply from the shared address, and manage the mailbox without logging in separately.

Shared mailboxes don’t require an additional Microsoft 365 licence as long as the mailbox stays under 50GB of storage, making them a cost-effective option for most businesses. If you need more storage, or require features like litigation hold or archiving, an Exchange Online Plan 2 licence will be needed.

 

 

 

Shared Mailboxes vs Distribution Lists: Which Should You Use?

 

This is a common point of confusion and worth addressing directly. Both shared mailboxes and distribution lists involve multiple people receiving the same emails, but they work very differently.

A distribution list delivers a copy of incoming emails to each individual member’s personal inbox. There’s no shared view, no shared history, and no ability to reply from the group address without specific configuration. Distribution lists are best for one-way or broadcast communication, sending announcements or updates to a group.

A shared mailbox gives everyone access to the same central inbox, with a shared view of all conversations. Team members can see what’s been replied to, who handled what, and what’s still outstanding. Replies come from the shared address rather than from individuals’ personal addresses.

If your business needs a central address where a team collaborates on responses, rather than simply receiving the same emails in their individual inboxes, a shared mailbox is the right choice. For a fuller comparison of the different Microsoft 365 group types, see our guide to managing distribution lists in Microsoft 365.

 

 

 

Understanding Shared Mailbox Permissions

 

Microsoft 365 uses three separate permission types for shared mailboxes, and understanding the difference matters for both functionality and security:

Full Access allows a user to open and manage the shared mailbox; reading emails, organising folders, creating drafts, and managing the shared calendar. Full Access on its own does not allow the user to send emails from the shared address.

Send As allows a user to send emails that appear to come directly from the shared mailbox address. The recipient sees only the shared address in the From field (for example, support@yourcompany.com) and replies return to the shared mailbox. This is the most commonly used sending permission for customer-facing shared mailboxes, as it maintains a consistent brand identity.

Send on Behalf allows a user to send from the shared mailbox while showing their own name alongside it — for example, “Jane Smith on behalf of support@yourcompany.com.” This is typically used in administrative or assistant workflows where the sender’s identity should remain visible.

Most users will need both Full Access and Send As permissions assigned. These are configured through the Microsoft 365 admin centre or the Exchange admin centre, and permission changes can take up to 60 minutes to propagate across devices, worth knowing if a new team member reports that access isn’t working immediately.

How to Create a Shared Mailbox in Microsoft 365

 

Creating a shared mailbox requires administrator access. The process through the Microsoft 365 admin centre is straightforward:

Sign in at admin.microsoft.com and navigate to Teams & groups → Shared mailboxes. Select Add a shared mailbox, enter a display name and email address for the mailbox (for example, support@yourcompany.com) and save. Once created, add members by selecting the mailbox and managing membership under the Members section. Assign the appropriate permissions (Full Access and Send As for most users) and save.

Members will typically find the shared mailbox appears automatically in their Outlook within a short period. If it doesn’t appear, they can add it manually through Outlook’s account settings.

Security Considerations for Shared Mailboxes

 

One important point that Microsoft is explicit about: a shared mailbox should never be used for direct sign-in. The mailbox has an associated user account, but sign-in for that account should always be blocked in the Microsoft 365 admin centre. Team members access the shared mailbox through their own accounts, not through any credentials associated with the mailbox itself.

From a broader security perspective, shared mailboxes benefit from the same protective measures as the rest of your Microsoft 365 environment:

Regular access reviews — permissions should be audited periodically and removed promptly when team members leave or change roles. A former employee retaining access to a customer-facing shared mailbox is a data governance and security risk that’s easily avoided with routine housekeeping.

Conditional Access — Microsoft Entra ID Conditional Access policies apply to shared mailbox access through your users’ accounts, providing the same location and device-based access controls that protect the rest of your Microsoft 365 environment.

Audit logging — Microsoft 365 logs user actions within shared mailboxes, providing a trail of who read, sent, or deleted what. For businesses with compliance obligations, enabling and retaining these audit logs is worth doing from the outset.

Best Practices for Managing Shared Mailboxes

 

The technology is straightforward. The challenge with shared mailboxes is usually people and process rather than the platform itself.

Define clear ownership. Every shared mailbox should have a named owner (typically a team leader or manager) responsible for managing membership, reviewing access, and ensuring the mailbox is being used correctly. Without clear ownership, shared mailboxes tend to accumulate stale members and missed emails over time.

Establish response expectations. Who is responsible for responding to messages in the shared mailbox, and within what timeframe? Without clear expectations, emails either get replied to twice or not at all. Simple conventions (such as moving an email to a “In Progress” folder when someone picks it up) go a long way.

Use folders to organise. Shared mailboxes support the same folder structure as personal mailboxes. Creating folders for different types of enquiry, or for archiving resolved conversations, keeps the inbox manageable as volumes grow.

Keep the address simple. Shared mailbox addresses that are clear and descriptive (support@, accounts@, info@) are easier for customers and colleagues to remember and less likely to be misused.

Review storage regularly. At 50GB, most shared mailboxes won’t hit the storage limit quickly, but for high-volume mailboxes handling large attachments, it’s worth monitoring. Mailboxes approaching the limit may experience delivery issues before the limit is formally reached.

Consider Power Automate for repetitive workflows. For shared mailboxes handling high volumes of similar enquiries, Microsoft Power Automate can automate repetitive tasks; routing emails based on keywords, sending acknowledgement replies, or triggering notifications to specific team members. This is particularly useful for support@ or enquiries@ mailboxes where triage takes significant manual effort.

When a Shared Mailbox Isn’t the Right Tool

 

Shared mailboxes work well for teams of up to around 25 concurrent users managing moderate email volumes. For larger teams, higher volumes, or more complex workflow requirements, they can start to show their limitations.

If your team needs shared resources beyond email, a shared calendar, file storage, integration with Microsoft Teams, or collaborative project management, a Microsoft 365 Group may be the better foundation. Microsoft 365 Groups provide a shared mailbox equivalent alongside a Teams channel, SharePoint site, shared calendar, and Planner integration.

For businesses handling very high volumes of customer enquiries with requirements for ticketing, SLA tracking, and detailed reporting, a dedicated helpdesk platform may be worth considering alongside or instead of a shared mailbox.

Managing Microsoft 365 for Your Business

 

Shared mailboxes are one of many Microsoft 365 features that benefit from proper initial configuration and ongoing management. Getting permissions right, ensuring security settings are in place, and keeping access up to date are all straightforward tasks, but they require consistent attention that many businesses without dedicated IT resource find difficult to maintain.

At Via Wire, we manage Microsoft 365 environments for businesses of all sizes,  including shared mailbox setup, permissions management, and ongoing administration. Get in touch today to discuss Microsoft 365 management for your business.