Permission & Access Issues

How to Access Outlook and SharePoint Across Two Microsoft 365 Tenants

Olivia Miller Sep 25, 2026 869 views

Question details

The user needs to seamlessly access multiple Microsoft 365 accounts, including Outlook mailboxes and SharePoint files, across different tenants without the need to repeatedly sign in and out.

How to Access Outlook and SharePoint Across Two Microsoft 365 Tenants

Product: Microsoft 365
Device & OS: not provided
Scenario: Working across multiple organizations or Microsoft 365 tenants and needing simultaneous access to communication and file resources.
Observed behavior: The user wants to establish a unified workflow to avoid the friction of logging out of one tenant to access resources in another.

Before you start

Ensure you have the login credentials for both Microsoft 365 accounts and verify with your IT administrators that cross-tenant collaboration or external guest access is permitted in both organizations.

Solution 1Recommended

Add the Second Account Directly in Microsoft Outlook

Use this solution to manage emails from two different Microsoft 365 tenants side-by-side within the Outlook desktop application.

The Outlook desktop client natively supports adding multiple Exchange or Microsoft 365 accounts, even if they belong to entirely different organizations or tenants. This is the fastest way to avoid signing in and out for emails.

Open Outlook Account Settings

Launch the Microsoft Outlook desktop application. Click on the 'File' tab in the top-left corner of the window.

Add a New Account

Under the 'Info' tab, click the 'Add Account' button located above your current account settings.

Authenticate the Second Tenant

Enter the email address associated with the second Microsoft 365 tenant and click 'Connect'. Enter your password and complete any Multi-Factor Authentication (MFA) prompts required by the second organization.

Restart Outlook

Once the account is successfully added, restart Outlook. Both mailboxes will now appear in your left-hand navigation pane.

Add the Second Account Directly in Microsoft Outlook

Unified Inbox Setup: By adding the account directly to the client, you will receive notifications for both tenants simultaneously.

Solution 2

Configure SharePoint Access via Microsoft Entra B2B

Use this method to access SharePoint files across tenants. It requires IT administrator action to configure guest access.

Free Microsoft Office alternative

Manage Your Documents Seamlessly Across Accounts with WPS Office

While Microsoft 365 requires complex Entra ID configurations for cross-tenant access, dealing with downloaded files shouldn't be a hassle. WPS Office offers a lightweight, unified workspace where you can easily open, edit, and save documents regardless of which tenant they originated from.

1. Download and Install WPS Office: Get the free WPS Office suite from the official website and install it on your computer.
2. Open Your Office Documents: Double-click any downloaded Word, Excel, or PowerPoint file from your different SharePoint tenants to open them instantly.
3. Edit and Save Seamlessly: Edit your documents and save them locally or directly back to your synced cloud folders without worrying about tenant login conflicts.

Free, lightweight, and fast office suite for all your document needsFully compatible with Microsoft Word, Excel, and PowerPoint formatsUnified tabbed interface to manage multiple documents in one windowNo complex tenant or account configurations required for local file collaboration

microsoft office alternative - wps office

Frequently Asked Questions

Can I use browser profiles to access two Microsoft 365 tenants at the same time?

Yes. A highly effective workaround for accessing web versions of Outlook and SharePoint across different tenants is to use separate browser profiles (e.g., in Microsoft Edge or Google Chrome). Each profile maintains its own cookies and session data, preventing sign-in conflicts.

Why am I getting a 'You don't have permission to access this resource' error in SharePoint?

This error typically occurs if your account has not been added as a guest in the host tenant's Microsoft Entra ID, or if the organization's external collaboration policies restrict external sharing. Your IT admin will need to adjust the B2B settings.

Does adding a second account in Outlook merge the two mailboxes?

No. When you add a second Microsoft 365 account in the Outlook desktop app, the mailboxes remain completely separate. They will appear as distinct folders in your left navigation pane, keeping your emails, calendars, and contacts isolated.

Document & File Issues