Use Spam Reporting Add-ins in New Outlook After Switching From Classic Outlook

When you move from classic Outlook to the new Outlook for Windows, your spam reporting add-ins may stop working. Classic Outlook supports COM add-ins, while new Outlook only supports web-based add-ins from AppSource. This article explains how to find, install, and use spam reporting add-ins in new Outlook so you can continue reporting junk emails the way you prefer.

Why Spam Reporting Add-ins Stop Working After Switching to New Outlook

Classic Outlook uses COM add-ins, which are executable programs that integrate deeply with the Outlook client. These add-ins run as separate processes and have direct access to the Outlook object model. When you switch to new Outlook, the application architecture changes. New Outlook is a web-based wrapper that runs on a different runtime environment. It does not support COM add-ins at all.

Microsoft designed new Outlook to use only web-based add-ins that are hosted on the AppSource platform. These add-ins run in a sandboxed browser environment and communicate with Outlook through a standard API. Spam reporting add-ins from third-party vendors such as Mimecast, Proofpoint, Barracuda, or Avanan must provide a web-based version of their tool to work in new Outlook. If your vendor has not published an AppSource add-in, the tool will not appear in new Outlook.

Another common cause is that the add-in was installed per-machine or per-user through a classic installer. New Outlook does not read the same registry keys or add-in configuration that classic Outlook uses. Even if the add-in appears in classic Outlook, new Outlook will not detect it.

Steps to Install and Use a Spam Reporting Add-in in New Outlook

Follow these steps to find and install a spam reporting add-in in new Outlook. You need an active internet connection and an AppSource account tied to your Microsoft 365 work or school account.

1. Open new Outlook and go to the ribbon
   Launch new Outlook for Windows. In the main Outlook window, look at the top ribbon. Click the Home tab if it is not already selected.
2. Click the Get Add-ins button
   On the right side of the Home tab ribbon, locate and click the Get Add-ins button. This opens the AppSource add-in store inside Outlook.
3. Search for your spam reporting add-in
   In the AppSource window, type the name of your spam reporting provider in the search box. Examples: Mimecast, Proofpoint, Barracuda, Avanan, or SpamAssassin. Press Enter.
4. Select the correct add-in from the results
   Review the search results. Look for the add-in published by your email security vendor. Click the add-in tile to open its details page.
5. Click the Add button
   On the add-in details page, click the Add button. A confirmation dialog may appear asking for permissions. Review the permissions and click Continue or Add again.
6. Wait for installation to complete
   The add-in installs within a few seconds. A success message appears. Close the AppSource window.
7. Find the add-in in the ribbon
   After installation, the spam reporting add-in appears as a new button on the Home tab. The exact location depends on the add-in. Look for a button with the vendor name or a custom icon.
8. Test the add-in with a junk email
   Select a test email from your Inbox. Click the spam reporting add-in button. The add-in should open a dialog or send a copy of the email to your security vendor for analysis.

If the add-in does not appear after installation, close and reopen new Outlook. The add-in loads when Outlook restarts.

Common Issues When Using Spam Reporting Add-ins in New Outlook

My spam reporting add-in is not in AppSource

Not all spam reporting tools have a web-based version. Contact your email security vendor and ask if they offer an AppSource add-in for new Outlook. If they do not, you have two options. You can stay on classic Outlook and continue using the COM add-in. Or you can use the built-in Junk button in new Outlook to manually report spam to your vendor by forwarding the email to a specific address provided by your security team.

The add-in installed but the button is grayed out

A grayed-out button usually means the add-in requires specific permissions or a license. Open the add-in details from AppSource and check the permissions section. Also confirm that your Microsoft 365 account has the correct license for the add-in. Some spam reporting add-ins require an admin to assign the add-in to users through the Microsoft 365 admin center.

The add-in asks for permission to read all emails

Spam reporting add-ins need permission to read and send emails on your behalf. This is normal because the add-in must forward the selected email to your security vendor. Review the permission request carefully. If the add-in is from a trusted vendor, grant the permission. If you are unsure, contact your IT department before approving.

The add-in works in classic Outlook but not in new Outlook

This is expected. Classic Outlook and new Outlook use different add-in platforms. You must install the add-in separately in new Outlook from AppSource. The classic COM add-in will never load in new Outlook. Uninstall the classic version if you no longer need it to avoid confusion.

Item	Classic Outlook	New Outlook
Add-in type supported	COM add-ins and web add-ins	Web add-ins only from AppSource
Installation method	Installer .exe or .msi file	AppSource store inside Outlook
Permission model	Full trust, runs in Outlook process	Sandboxed, permission-based API
Spam reporting example	Mimecast for Outlook COM add-in	Mimecast for New Outlook web add-in
Admin deployment	Group Policy or manual install	Integrated Apps in Microsoft 365 admin center

After switching to new Outlook, you can continue reporting spam using a web-based add-in from AppSource. First check that your vendor offers an AppSource add-in. Then install it from the Home tab using the Get Add-ins button. If your vendor does not have a web add-in, use the built-in Junk button or forward spam to your security team. You can also ask your IT admin to deploy the add-in centrally through the Microsoft 365 admin center under Settings > Integrated Apps.