Hello,
I fear someone might have set up email forwarding from your account, to forward every single email you received to a different address.
To confirm this, make sure you do this on a computer, not on smartphone or tablet. Go to https://www.outlook.com and log in, click on the gear icon in the top right to launch the settings.
Then, on the Mail tab, go to Rules. Are there any rules set up here? If yes, delete them all.
Then check the conditional transfer, again, if it's there, delete it.
Then, check Forwarding and IMAP, If any items are present, delete them as well.
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If you can't find anything, go to https://account.live.com > Your info > Sign in Preferences. Make sure to check all the aliases here. If you don't recognize any there, delete it.
Then go to Security > Manage How I sign in, make sure all contact info is yours.
Please make sure you change your password and enable two-step verficiation.