How to Open and Access a Shared Mailbox in Microsoft Outlook on Windows and Web

In many businesses, educational institutions, and collaborative environments, teams rely on generic or shared email addresses—such as [email protected], [email protected], or [email protected]—to handle client queries and departmental communications. Microsoft 365 manages these through shared mailboxes, allowing multiple assigned colleagues to monitor a centralised inbox, categorise incoming threads, and send replies using the shared address without requiring a separate paid user licence.

While Microsoft Exchange administrators typically configure auto-mapping to display shared accounts automatically, auto-mapping can occasionally take hours to propagate or fail entirely. Furthermore, working within Outlook on the web requires a distinct set of navigation steps. This guide walks you through manually opening and accessing a shared mailbox across the classic Microsoft Outlook desktop client, the new Outlook for Windows, and Outlook on the web, alongside best practices for sending messages as the shared alias.

Understanding Permissions: Full Access vs Send As

Before attempting to add or view a shared mailbox, your Microsoft 365 global administrator or Exchange tenant manager must grant your user account the appropriate permissions:

• Full Access (Read and Manage): Allows you to open the shared mailbox, read incoming correspondence, create subfolders, flag items, and delete emails. However, Full Access alone does not permit you to send messages appearing from the mailbox address.
• Send As: Permits you to send new emails or replies where the recipient sees only the shared mailbox address in the “From” header.
• Send on Behalf Of: Permits you to send messages where recipients see a header indicating “User on behalf of Shared Mailbox”.

Ensure your administrator has assigned both Full Access and Send As permissions to guarantee a smooth, frictionless daily workflow.

Method 1: Accessing a Shared Mailbox in Outlook on the Web (OWA)

Outlook on the web provides two distinct methods for accessing shared mailboxes: adding the folders directly to your primary folder tree, or opening the mailbox in a dedicated browser tab.

Option A: Adding Shared Folders Directly to Your Folder Pane

1. Navigate to outlook.office.com in your browser and sign in with your primary Microsoft account credentials.
2. In the left navigation folder pane, right-click on Folders (or right-click your account display name).
3. Select Add shared folder or mailbox from the contextual menu.
4. A dialogue box will appear prompting you to enter the name or email address of the shared mailbox. Type the shared address and select it from the directory list.
5. Click Add.

The shared mailbox will immediately appear at the bottom of your folder hierarchy in the left sidebar, allowing you to browse its Inbox, Sent Items, and custom folders side-by-side with your personal mail.

Option B: Opening the Mailbox in a Dedicated Browser Window

Opening the shared mailbox in its own tab gives you a clean, dedicated workspace and ensures all outgoing messages automatically default to the shared alias without manual address swapping.

1. Click your Profile photo or initials icon in the upper right corner of the Outlook on the web navigation bar.
2. Click Open another mailbox.
3. Enter the email address of the shared mailbox in the search dialogue.
4. Select the mailbox from the directory and click Open.

Outlook will open a separate browser tab loading the complete shared account, complete with its own calendar, contacts, and focused inbox view.

Method 2: Opening a Shared Mailbox in Classic Outlook for Windows

If auto-mapping has not displayed the mailbox in your desktop Outlook client, you can link it directly via your existing account settings without setting up a secondary account profile.

1. Open the classic Microsoft Outlook desktop application.
2. Click the File tab in the ribbon at the top left corner.
3. With the Info section selected, click Account Settings and choose Account Settings from the dropdown list.
4. In the Email tab, click to highlight your primary Microsoft 365 Exchange account, then click Change.
5. Click the More Settings button in the dialogue window.
6. Navigate to the Advanced tab.
7. Under the Mailboxes section, click the Add button.
8. Type the exact name or email address of the shared mailbox, then click OK.
9. Click Apply, then click OK to close the Advanced settings dialogue.
10. Click Next and then Finish. Close the Account Settings dialogue.

Return to your main Outlook window. After a brief synchronisation interval, the shared mailbox will appear in your left-hand folder navigation list beneath your personal folders.

Method 3: Opening a Shared Mailbox in the New Outlook for Windows

The modernised “New Outlook for Windows” interface shares the design architecture of Outlook on the web, making the configuration process straightforward:

1. Launch the New Outlook for Windows application.
2. In the left folder navigation sidebar, locate and right-click your account header or the Shared with me header.
3. Select Add shared folder or mailbox.
4. Type the email address of the shared mailbox into the search input.
5. Select the matching mailbox from the directory results and click Add.

How to Send Emails from the Shared Mailbox Address

Once you have access, replying to messages or composing new emails under the shared name requires enabling the “From” selector in your composer window:

1. Click New Mail (or click Reply on an existing thread within the shared folder).
2. If the From field is not visible above the “To” line, navigate to the Options tab in the ribbon and click From (or click the three dots menu in Outlook on the web and choose Show From).
3. Click the From dropdown button and select Other Email Address….
4. Click From… to select the shared mailbox from the Global Address List, or type the exact shared address and click OK.

Outlook will remember this address. In subsequent messages, you can simply click the From dropdown arrow and pick the shared mailbox alias with a single click.

Resolving Common Shared Mailbox Synchronisation Problems

If you encounter difficulties accessing folders or sending emails from the shared address, consider the following troubleshooting steps:

• Permission Propagation Delays: When an administrator assigns permissions in Microsoft 365 admin centre or Exchange Online PowerShell, changes can take between 15 minutes and several hours to replicate across Microsoft servers. Allow sufficient time before re-testing.
• Sent Items Stored in Personal Folder: By default in older Exchange configurations, emails sent using a shared address were saved into the personal user’s Sent Items folder. Ensure your Exchange administrator has enabled the MessageCopyForSentAsEnabled setting on the mailbox so all team members can see outgoing correspondence in the shared Sent Items folder.
• Cached Exchange Mode Glitches: If folders fail to refresh in desktop Outlook, navigate to File > Account Settings > Account Settings > Change > More Settings > Advanced and uncheck Download shared folders. This forces Outlook to connect to the shared mailbox in online mode, eliminating local cache sync errors.