******@notificationmail.microsoft.com : "Your Microsoft storage is almost full" - although < 0,1 GB

Question

Today, I got an email from ******@notificationmail.microsoft.com with subject "Your Microsoft storage is almost full", inside: "Your storage is over 80% full" by IMAP in my Betterbird.

After checking the mail headers (Ctrl-U), it seems no phishing (helo=r81.engagement.microsoft.com):

Received: from [10.1.1.151] ([10.1.1.151:37261] helo=r81.engagement.microsoft.com) by or2-prod1-mta-b-i-06dc65b8c12c587f7 (envelope-from <******@notificationmail.microsoft.com>) (ecelerity 4.4.1.20033 r(msys-ecelerity:tags/4.4.1.0^0)) with ESMTP id 32/58-16460-00B2CB96; Thu, 19 Mar 2026 16:57:36 +0000
From: "Microsoft" <******@notificationmail.microsoft.com>
Date: Thu, 19 Mar 2026 09:57:32 -0700
Subject: Your Microsoft storage is almost full

So I clicked the link "Manage storage": https: //t.notificationmail.microsoft.com/r/?id=h...f , it shows my MS account. Clicking on the account details, I see "Microsoft storage < 0.1 GB / 5 GB".

The same picture accessing "outlook.live.com" -> Files -> Account Info -> Storage :
Microsoft Storage - Total used < 0.1 GB / 5 GB
Email storage - Total used < 0.1 GB / 15 GB
Manage storage - each folder < 5 MB (not GB!)

Is it a "false positive" by Microsoft?
Will my account be locked after the next mail with an attachment of...let's say 2 MB (actually 6 MB used in mail folders and detected as 80%)?

Answer 1

The message indicates that Microsoft’s backend has determined the unified cloud storage is near its quota, even though the visible storage meters currently show less than 0.1 GB used. This can happen when:

• The unified storage system has recently changed or been recalculated, and the warning email is based on older or partially updated data.
• Background processes (e.g., OneDrive sync, Outlook.com attachments, or other Microsoft 365 app data) temporarily push usage near the threshold before the UI reflects the final numbers.

What is important is how Microsoft enforces limits:

• When Microsoft storage is actually exceeded:
  • Uploading, editing, or syncing new files to OneDrive is blocked and existing files become read-only.
  • Sending or receiving email in Outlook.com is blocked, even if the email storage quota itself is not exceeded.
  • Sending or receiving Microsoft Teams messages with attachments is blocked.
  • After 6 months over the limit, OneDrive and its files may be deleted.
• When only email storage is exceeded:
  • Sending and receiving email in Outlook.com stops, and senders get a “mailbox full” error until storage is reduced.

In the current state (UI showing <0.1 GB of 5 GB and <0.1 GB of 15 GB), the account is not actually over quota and will not be locked or blocked from receiving a small attachment such as 2 MB. The warning email is effectively a false positive or a lagging notification.

If a similar warning appears again while the storage meters still show well below quota, the recommended actions are:

1. Sign in to Outlook.com and use Manage Outlook.com storage to confirm which folders and items are consuming space.
2. Verify OneDrive usage in the same Microsoft account, since OneDrive files and Outlook.com attachments share the same 5 GB Microsoft storage pool.
3. If any cleanup or deletion is performed, allow up to 24–48 hours for the storage status to fully update across services.

Only when the unified storage or email storage indicators show that the quota is actually exceeded will sending/receiving be blocked.

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References:

• Storage limits in Outlook.com
• Microsoft storage FAQs
• Why did I get a 'ran out of storage space' message in Microsoft To Do?