Are Third-party Account Add-ins in New Outlook? Current Support Status and Workaround

Many users who rely on third-party email services such as Gmail, Yahoo, or iCloud in the classic Outlook are now asking whether the new Outlook for Windows supports add-ins for these accounts. The new Outlook, built on a web-based platform, has a different architecture that does not currently allow third-party account add-ins to function the same way as in classic Outlook. This article explains the current support status for third-party account add-ins in new Outlook and provides a practical workaround to regain functionality.

Why New Outlook Does Not Support Third-party Account Add-ins

The new Outlook for Windows is built using the same technology as Outlook on the web (OWA). This web-based architecture uses a unified mail engine that processes all accounts through a single pipeline. In this design, third-party accounts like Gmail and Yahoo are handled via IMAP or OAuth connections, not through the same add-in framework that classic Outlook uses.

Classic Outlook uses a COM-based add-in system that allows third-party add-ins to interact directly with the local data store (PST or OST files) and the MAPI subsystem. New Outlook does not have a local data store. It caches data in a web-based format and does not expose the same interfaces for add-ins. As a result, add-ins designed for third-party accounts in classic Outlook cannot load or function in new Outlook.

What Are Third-party Account Add-ins?

Third-party account add-ins are small programs that extend the functionality of Outlook for non-Microsoft email accounts. Examples include add-ins that integrate CRM tools, email tracking services, or productivity apps specifically for Gmail or Yahoo accounts. These add-ins rely on the classic Outlook add-in framework to access the account’s data and UI elements.

What Add-ins Work in New Outlook?

New Outlook supports only web-based add-ins from the Microsoft AppSource store. These add-ins are designed to work within the OWA framework and are available for all account types, including third-party accounts. However, they are limited to the functionality provided by the add-in’s web interface and do not have the same deep integration as classic Outlook add-ins.

Steps to Check Add-in Compatibility in New Outlook

Before looking for a workaround, verify which add-ins are available and compatible with your new Outlook setup.

1. Open new Outlook and go to Add-ins
   In the new Outlook window, click the Get Add-ins button on the Home tab. This opens the Microsoft AppSource store within Outlook.
2. Search for your add-in by name
   Type the name of the add-in you use in classic Outlook into the search bar. Check if it appears as a web-based add-in available for installation.
3. Install the add-in if available
   If the add-in appears, click Add to install it. It will then appear in the add-in pane when you select a message or create a new email.
4. Test the add-in with a third-party account
   Select an email from your Gmail, Yahoo, or iCloud account and open the add-in pane. If the add-in works, it will display its interface. If it does not load, it means the add-in is not compatible with third-party accounts in new Outlook.

Workaround: Switch Back to Classic Outlook

If your required third-party account add-ins are not available in new Outlook, the only complete workaround is to switch back to classic Outlook. Microsoft has not provided a timeline for when or if third-party account add-in support will be added to new Outlook.

1. Locate the toggle switch
   In the upper-right corner of the new Outlook window, find the toggle that says Try the new Outlook. Click it to turn it off.
2. Confirm the switch
   A dialog box appears asking if you want to switch back to classic Outlook. Click Yes.
3. Wait for classic Outlook to open
   Classic Outlook will relaunch. Your third-party accounts and their add-ins will be available again.
4. Pin classic Outlook to the taskbar
   To prevent accidentally switching to new Outlook again, right-click the Outlook icon on the taskbar and select Pin to taskbar. This keeps classic Outlook easily accessible.

If You Cannot Use Classic Outlook

Use a Third-party Email Client Instead

If your organization requires you to use new Outlook and you cannot switch back, consider using a separate email client for your third-party accounts. Applications like Mozilla Thunderbird or eM Client support add-ins and extensions for Gmail, Yahoo, and iCloud accounts.

Use the Web Interface for Third-party Accounts

Another workaround is to access your third-party account directly through its web interface. For example, log in to Gmail in a browser and use the add-ins available in the Gmail web interface. This is not integrated with Outlook but preserves the add-in functionality.

Wait for Microsoft to Update Support

Microsoft has stated that new Outlook will eventually support more add-in types. Check the Microsoft 365 Roadmap periodically for updates on third-party account add-in support. As of now, no specific date has been announced.

New Outlook vs Classic Outlook: Add-in Support Comparison

Item	New Outlook	Classic Outlook
Third-party account add-ins	Not supported	Supported for all account types
Web-based add-ins from AppSource	Supported for all accounts	Supported but limited to web add-ins
COM add-ins	Not supported	Fully supported
Local data store integration	No local store	Uses PST/OST files
Add-in installation method	AppSource store only	File > Options > Add-ins or direct installation

New Outlook does not support third-party account add-ins due to its web-based architecture. The only workaround that preserves full add-in functionality is to switch back to classic Outlook. For users who must stay in new Outlook, using web-based add-ins from AppSource or accessing third-party accounts through their native web interfaces are temporary alternatives. Monitor the Microsoft 365 Roadmap for future updates on add-in support for third-party accounts in new Outlook.