Hello, thank you for reaching out to Microsoft Q&A.
With a Microsoft account (without any Office 365 Subscription), you get 5GB of OneDrive Cloud Storage and 15GB of Outlook email storage. If you exceed any one of the limits, you won't be able to send or receive emails normally.
As you have already checked your OneDrive space, please check your Outlook storage space as well by signing in with your account here-
https://outlook.live.com/mail/0/options/accounts-category/storage
Expand the email storage section and see if you have enough space there.
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If you exceed the storage limit, your account will be placed in a frozen state.
After you upgrade your storage or free up space in your account, it typically takes up to 24 hours for the account to unfreeze and return to normal. After 24 hours, I recommend that you sign out and then sign back in to Outlook.com, and then check whether you can send and receive emails again.
In the meantime, if possible, try deleting additional files from OneDrive so you don’t encounter the same issue again. You can use the link above to identify which large files are taking up space in your OneDrive.
