Using classic Outlook for Windows in business environments
Greetings, Cátia! My name is Arif, I'd be pleased to help you as a Microsoft adviser.
Please take the following actions:
Dear Cátia, I have read message and you had great job that you have reset your password and check your Microsoft account security but try to enable 2FA authentication as soon as possible you can and keep monitoring your account on web on the security tab in case you notice any other device try to login your account or notice that your account logged in from any other location.
If in case this happen again reset your Microsoft account password and try to add on your password 10 to 12 characters, use a combination of letters, numbers, and symbols.
Make sure to block the sender email address, for more information please check the article below which is related to your issue:
https://support.microsoft.com/en-us/office/bloc...
If the steps outlined above work for you, kindly let me know. If not, please feel free to respond to my chat.
Warm Regards,
Arif