This usually means someone tried to sign in to your Microsoft account or trigger a login verification. Even if you did not request it, the safest assumption is that someone else has your email address and is attempting access, not that your account is already fully compromised.
Do not click anything in the email and do not respond to it. Instead, go directly in your Android browser to https://account.microsoft.com/security and sign in manually. Once there, review recent activity and look for any sign-in attempts you do not recognize. If you see anything suspicious, change your password immediately to a strong, unique one that you have not used anywhere else.
After changing your password, make sure two-step verification is enabled so future login attempts require your approval. You can also sign out of all devices from the security page to cut off any active sessions that may already be logged in.
If your Microsoft account password is reused anywhere else, change those accounts as well, starting with email, banking, and social media, because attackers often try the same credentials across services.
On your Android phone, also check that your email app is the official Microsoft Outlook or Gmail app and not a third-party app you don’t recognize, and ensure your phone is updated to the latest security patch level.
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hth
Marcin