Classic Outlook users who manage multiple email accounts often rely on add-ins to extend functionality for each mailbox. When switching to the new Outlook, add-ins behave differently for secondary accounts, leaving some users unable to access their tools. This article explains how add-in permissions work in the new Outlook for accounts added after the primary mailbox. You will learn which add-ins are available, how to enable them, and what limitations classic Outlook users should expect.
Key Takeaways: New Outlook Secondary Account Add-ins
- Settings > Mail > Add-ins: Manage add-in permissions for each secondary account independently from the primary mailbox.
- Admin-managed add-ins: Centralized add-ins deployed by IT may not appear automatically for secondary accounts unless explicitly assigned.
- COM add-ins: Classic Outlook COM add-ins do not load in the new Outlook; use web-based add-ins instead.
How Add-in Permissions Differ Between Primary and Secondary Accounts
In classic Outlook, add-ins installed for the primary mailbox often apply to all accounts in the same profile. The new Outlook changes this model. Each account, whether primary or secondary, stores its own add-in permissions and settings. This shift prevents a single add-in from accessing data across multiple mailboxes without explicit consent.
The new Outlook uses a web-based add-in platform that relies on Exchange Web Services and REST APIs. When you add a secondary account, the new Outlook does not automatically copy add-in assignments from the primary account. You must enable each add-in separately for every account where you want it to appear. This design improves security by limiting cross-account data access and aligns with modern permission models used in Outlook on the web.
Why Secondary Accounts Lose Add-ins by Default
When you add a secondary account in the new Outlook, the app treats it as a separate identity. Add-in manifests are tied to the user identity and the mailbox GUID. The new Outlook does not share add-in state between accounts. If you previously relied on a single add-in installation in classic Outlook to cover all accounts, you will need to enable it manually for each secondary account in the new Outlook.
Steps to Enable Add-ins for a Secondary Account in New Outlook
- Open new Outlook settings
Click File in the ribbon, then select Options. Alternatively, click the gear icon in the upper-right corner and choose View all Outlook settings. - Navigate to the Add-ins page
In the settings panel, go to Mail and then click Add-ins. This page lists all available add-ins for the currently selected account. - Select the secondary account
At the top of the Add-ins page, click the account selector dropdown. Choose the secondary account for which you want to enable add-ins. - Enable the desired add-ins
Find the add-in you want to use and click the toggle switch to turn it on. Repeat for each add-in you need for this account. - Verify add-in visibility
Switch to the secondary account in the main Outlook window. Open a message or calendar item to confirm the add-in appears in the ribbon or reading pane.
Enable Admin-Deployed Add-ins for Secondary Accounts
If your organization uses centralized add-in deployment, the new Outlook may not automatically assign those add-ins to secondary accounts. To check availability:
- Open the Microsoft 365 admin center
Sign in with your admin credentials and go to Settings > Integrated apps. - Select the add-in deployment
Click the add-in name and then choose Manage. Review the user and group assignments. - Add the secondary account identity
If the add-in is assigned to users by email address, ensure the secondary account email is included in the target group. If using group-based assignment, add the secondary account to the appropriate security group. - Wait for sync and verify
Changes may take up to 24 hours to propagate. After that, open the secondary account in new Outlook and check the Add-ins page.
Limitations and Add-in Types That Do Not Transfer
COM Add-ins Are Not Supported in New Outlook
Classic Outlook supports COM add-ins, which are compiled DLLs or EXEs that integrate deeply with the Outlook object model. The new Outlook does not load COM add-ins. If you rely on a COM add-in for a secondary account, you must find a web-based alternative or continue using classic Outlook for that account. Examples of COM add-ins include custom CRM integrations, legacy PDF tools, and older productivity extensions.
Add-ins That Require Full Mailbox Access May Fail
Some add-ins request permissions to read or send mail from any account in the profile. The new Outlook restricts such broad permissions. If an add-in was granted full mailbox access in classic Outlook, it will not automatically receive the same access for secondary accounts. You may see a permission prompt when you first enable the add-in for the secondary account. Granting the permission is required for the add-in to function.
Add-in Ribbon Customizations Are Not Shared
Classic Outlook allows users to customize the ribbon and Quick Access Toolbar, including add-in buttons. These customizations are stored per profile, not per account. The new Outlook does not migrate these settings. After enabling an add-in for a secondary account, you may need to reposition its button in the ribbon using the new Outlook’s customizable toolbar options.
| Item | Classic Outlook | New Outlook |
|---|---|---|
| Add-in type support | COM, VSTO, web-based, Exchange | Web-based only (AppSource, custom web add-ins) |
| Add-in scope | Per profile, applies to all accounts | Per account, requires individual enablement |
| Admin deployment | Centralized via Exchange or Group Policy | Centralized via Integrated Apps in admin center |
| Permission model | Full mailbox access by default for installed add-ins | Granular permissions per add-in per account |
| Ribbon customization | Stored in profile, shared across accounts | Per account, not migrated from classic |
Common Add-in Issues for Secondary Accounts and How to Resolve Them
Add-in Does Not Appear for Secondary Account After Enabling
If you enabled an add-in for a secondary account but it does not show up, restart the new Outlook. The add-in may require a fresh login session to load its manifest. If the issue persists, remove the secondary account and add it again. Then repeat the enablement steps.
Add-in Works for Primary Account but Not for Secondary
This usually occurs when the add-in uses a license key tied to the primary email address. Contact the add-in vendor to request a license that covers the secondary account. Some add-ins allow you to enter multiple email addresses in their settings panel.
Error Message About Missing Permissions for Secondary Account
The new Outlook shows a permission prompt when an add-in requests access to the secondary mailbox. Click Accept to grant the permission. If the prompt does not appear, go to the Add-ins page for that account, disable the add-in, then enable it again to trigger the consent dialog.
Admin-Deployed Add-in Missing for Secondary Account
Check the admin center to confirm the secondary account email is included in the add-in assignment. If the add-in is assigned to a security group, add the secondary account to that group. After making changes, instruct the user to sign out of new Outlook and sign back in.
Conclusion
You can now enable add-ins for secondary accounts in the new Outlook by visiting Settings > Mail > Add-ins and selecting the account from the dropdown. Remember that each account requires individual enablement and that COM add-ins from classic Outlook will not work. For a smoother transition, identify web-based alternatives for your essential add-ins before switching fully. Test one secondary account first to confirm all required tools function correctly.