Managing personal Outlook.com account settings, security, and privacy
Dear Rachel Coster
Welcome to Microsoft Community.
I understand your concern about receiving unsolicited account verification codes. This definitely warrants investigation. Is this email comes from @accountprotection.microsoft.com? Microsoft uses this domain to send email notifications about your Microsoft account. These notifications can include security codes for two-step verification and account update information, such as password changes.
Anyway, since you haven't requested any verification codes, please don't click on any links in the message, it may be a phishing attempt.
The most likely possibility is that someone knows your email address and is sending this type of email to you in bulk, perhaps as a phishing attack, although this does not mean that your account has been compromised, just that someone else knows your email address. But, of course, you can continue to change your passwords and update your additional security information (your alternate email address, mobile phone number, etc.) to increase the security of your account before it's too late.
Please also read this article on what to do next if your account has been compromised: My Outlook.com account has been hacked - Microsoft Support Analyze your device thoroughly and change your password immediately according to the links and instructions in this article.
I hope the answers above can ease your concerns and solve your problem, I hope you and your account are safe forever, please feel free to let me know how it is going and contact me if you need any further assistance. :)
Best Regards
Schale.P-MSFT | Microsoft Community Support Specialist