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Also, people who send you email will receive an error message that tells you your mailbox is full. If it does exceed capacity, you won't be able to send or receive any messages. If your mailbox is nearing its maximum capacity, we will begin sending you emails and in-app messages telling you your storage is almost full. "Quota Exceeded, your account is above quota limits"
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Administrators can reduce maximum mailbox sizes per user or globally, see: How to set Exchange Online mailbox sizes and limits in the Microsoft 365 environment for details. Outlook accounts can have up to 100GB of storage per mailbox ( Exchange Online mailbox storage limits). Note: This support article is only applicable if you sign in with a work or school account.
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