Verwalten persönlicher Kontoeinstellungen, Sicherheit und Datenschutz für Outlook.com
Hello, thank you for reaching out.
With a Microsoft account, you get 5GB of OneDrive and 15GB of Outlook email storage.
If you exceed any one of the storage limits, you will not be able to send or receive emails.
Open a private browsing tab and sign in with your Microsoft account here.
https://outlook.live.com/mail/0/options/accounts-category/storage
Expand the 'Microsoft Storage Section' and 'E-mail Storage Section'.
(Post a screenshot of the page here)