What is a shadow.outlook account? Have I been hacked?

As a MacBook user, I am seeing this due to the presence of both the Legacy and new versions. After checking thoroughly, I found that no other files or folders have been created, except for the new and Legacy Outlook files.

Dear CatieRS

Welcome to Microsoft Community.

Based on what you have described, the “shadow.outlook.com” account is not a common email address format, which normally may indicate a security issue with your account. Here are some possible causes and solutions:

The account has been hacked:

A hacker may have created a “shadow” account that can be used to send spam or conduct other malicious activities.

We recommend that you change your Microsoft and Gmail account passwords immediately and enable two-step verification for added security.

Check account settings:

Log in to your Microsoft and Gmail accounts and check for any unknown forwarding rules or authorization applications.

Verify that no unfamiliar devices or locations are logged into your account.

Remove suspicious shadow mailboxes:

Log in to Outlook.com or use the Outlook desktop application and check for any suspicious folders (e.g. “Shadow Inbox”).

If you find a suspicious folder, right-click on it and select Delete.

In the meantime, you can also contact Microsoft support manually in the following ways and explain your problem so that they can try to check as well as deal with it for you:

In the meantime, you can also follow the following ways to communicate with Microsoft's human customer service:

1. Click the link.–Contact - Microsoft Support
2. In the box under “We're here to help,” enter Outlook, click Get Directions, and then click Contact Customer Service. (You must be logged into your Microsoft account. If not, follow step )
3. In this section, you need to sign in to your personal Microsoft account.

Note: You can only sign in with your personal MSA, when you sign in with your company account, it will not display correctly. If you are unable to connect to this account, you can use another account or create a new account to manage it.

4. Under “Products and Services”, select “Other Products”, select “Outlook”, and then click Confirm.
5. You can select “Chat with a Support Specialist in a Web Browser” and go to the chat window.

Note: Please contact us during local business hours on weekdays, CHAT is not available 24 hours a day.

You can also check the link to view the Microsoft phone number in your area for weekday contact:Global Customer Service phone numbers - Microsoft Support

Feel free to text back if you need further help.

Best wishes

Chris.S-MSFT | Microsoft Community Support Specialist

I followed the steps to get to a live chatbox - worked quickly. He gave me step by step instructions for how to remove and add my email to outlook. However, as I started, I got a pop up message that my email does not work with the new version of outlook, and there was a button to "revert" to the legacy version. When I did that, I tested by sending some emails before I went further in the process. Turned out that reverting resolved my problem!

Getting to the site wasn't intuitive but upon reaching it and the chat I was able to resolve the issue by removing and adding the email address. The chat instructions were clear and concise. Thank you.