Mailbox storage quota

Question

I keep getting emails that I am running out of storage but when I check my account - I see that I have many GB left. What's the deal?

Answer 1

Hi, I'm John! I will help you with this.

To help narrow down the issue:

1. Where did you get the storage message? Email or Windows notification?
2. Can you check the sender of the email? Does it look like a Microsoft address?

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If you’d like, please let me know whether you can sign in to OneDrive normally and what the sender’s email domain is (you can mask part of it).

Microsoft does send legitimate OneDrive storage warning emails, but there are also phishing emails that look very convincing.

To stay safe, here’s how to tell the difference:

• Don’t click any links in the email for now.
• Check the sender’s email address carefully. Official Microsoft emails usually end with @microsoft.com (not random domains or misspellings).
• Sign in to OneDrive directly to https://onedrive.live.com/managestorage in your browser (not link through the email). If there’s a real issue, you’ll see the warning after you sign in.
• In Outlook, look under Settings > Storage or OneDrive storage info to confirm if your account is over quota or inactive.

IMPORTANT: If the email is asking for urgent action, threatening immediate deletion, or asking you to “verify” your account, that’s a red flag and likely a scam.

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I really hope this information is helpful! Let me know if you have any further questions or concerns.

Regards,

John J.D.

Answer 2

I get emails from e.g. Cloud full <no reply @ ddd1-ab193.firebaseapp.com> saying "Your cloud is at 100% - Action required" daily, they are just junk spam. Delete and ignore if yours are like this.

Answer 3

Outlook.com and Microsoft accounts have two separate but related quotas, and warning emails can be triggered by either:

1. Email (Outlook.com mailbox) storage
   • Free Outlook.com accounts get 15 GB of email storage.
   • Microsoft 365 subscribers get 100 GB of mailbox space.
   • If the mailbox itself is near full, Outlook.com shows a "Quota Exceeded" or "Mailbox full" message.
   • To see actual mailbox usage and clean it up: open Outlook.com, go to Settings and search for Storage. There you can see which folders use the most space and bulk-delete items (including messages older than 3, 6, or 12 months).
2. Microsoft cloud (Unified) storage – OneDrive + attachments + apps
   • Every Microsoft account also has 5 GB of free cloud storage shared across OneDrive files, Outlook.com attachments, and Microsoft 365 apps.
   • If this cloud storage is full, you may see a "Microsoft Unified Storage is full" or "Microsoft storage limit exceeded" type message, even if the mailbox itself still shows plenty of email space.
   • When Microsoft storage is exceeded:
     • OneDrive becomes read-only and cannot sync new files.
     • Outlook.com cannot send or receive email, even if email storage is under its quota.
3. Why warnings appear when “many GB” look free
   • Often the mailbox (15 GB / 100 GB) is fine, but the 5 GB unified/cloud storage is over quota. The storage page being checked may show only email usage, not the unified storage usage that triggered the warning.
   • In some cases, warnings are sent to a secondary or older email address tied to a different Microsoft profile that is actually over its limit.
4. How to fix it
   • Check Outlook.com mailbox usage: Settings → Storage and clean up folders if needed.
   • Check Microsoft cloud/unified storage usage and free up space (for example, delete large OneDrive files or old attachments) or purchase more Microsoft storage if required.
   • If already a Microsoft 365 subscriber, consumer mailbox limits are capped at 100 GB; beyond that, space must be freed or an enterprise plan considered.

If the warning emails refer to being over 5 GB while the current account shows much less used, verify whether there is an older Microsoft/OneDrive profile or different email alias that is actually the one over quota.

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References:

• Microsoft storage quotas
• Storage limits in Outlook.com
• Mailbox storage limits in Outlook
• Microsoft storage limit exceeded - Microsoft Q&A
• storage exceeded in outlook after purchasing MS 365 subscription - Microsoft Q&A