Using classic Outlook for Windows in business environments
Dear Yuliia Shandyba
Thanks for using Microsoft products and posting in the Community.
For the issue of you being emailed a verification code, if it's not you logging in and verifying it yourself.
You can check for unusual login information by logging into your account at acccount.microsoft.com and checking for abnormal login information at Security - View Login Information.
If not, then it's a fraudulent email and you can delete it or ignore it, and don't click on any links in it in the front.
If there are unusual login details, it means your account has been compromised and hackers are constantly trying to crack your account.
You can change your password and use Microsoft Authenticator + 2FA to protect your account.
Download Microsoft Authenticator - Microsoft Support
Microsoft Authenticator allows you to log into your account with dynamic numbers, which can effectively prevent your account from being stolen by hackers.
Of course, hackers know your account, so they will keep trying to crack your account in the near future, but your account is in a secure state, so the hackers will give up logging into your account at a period of time because they can't crack your account.
Best wishes
Clark | Microsoft Community Support Specialist