Outlook mailbox 'full' issue

ryan o'neill 0 Reputation points
2026-05-28T09:37:09.31+00:00

Hi,

I upgraded to Microsoft 365 via Google Play. My Outlook.com on the bottom left still says 6.6GB of 5GB used.

But when I click on 'manage storage' it shows 6.6/100 GB used, OneDrive shows 6.6/100 GB, but I still cannot send emails. It says mailbox is full. This has been ongoing for 15+ hours.

Microsoft support chat referred me to Outlook support which has no live agent. Please can someone help escalate this.

Outlook | Web | Outlook.com | Email

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  1. AI answer

    2026-05-28T09:37:33.45+00:00

    The account shows a classic symptom of Microsoft cloud storage being over quota even though the upgraded limits are visible in the storage UI.

    Key points from the documented behavior:

    • If Microsoft cloud storage (unified storage) is exceeded, Outlook.com cannot send or receive email, even if the mailbox view shows enough email quota.
    • When storage is over quota, messages sent to the account are bounced and cannot be recovered.
    • After freeing space or purchasing storage, it can take up to 24–48 hours for the new quota and status to propagate across the account.

    Based on this, the most likely causes and actions are:

    1. Unified storage still considered over quota
      • Even though “Manage storage” shows 6.6/100 GB, the backend may still be treating the account as over the old 5 GB limit.
      • This is consistent with the “Microsoft Unified Storage is full” behavior: Outlook.com blocks sending/receiving until the unified storage state is updated.
    2. Wait for propagation
      • After upgrading storage, it can take up to 24–48 hours for the quota change to fully apply across Outlook.com and OneDrive.
      • Since it has been ~15 hours, the documented guidance is to wait up to the full 24–48 hours and then test sending again.
    3. Reduce storage as a workaround
      • While waiting for the quota update, reduce stored data to get clearly under any possible threshold:
        • Delete or move large emails and attachments in Outlook.com (especially in Inbox, Sent Items, Deleted Items, and Junk Email), then empty Deleted Items.
        • Remove or move large files from OneDrive to reduce overall Microsoft storage usage.
      • This aligns with the guidance that to restore sending/receiving, the account must be under the storage quota.
    4. Re-contact support if issue persists beyond 48 hours
      • If after 24–48 hours the storage indicators still show 6.6/100 GB but Outlook.com continues to report “mailbox is full” and block sending, this indicates a backend issue that must be resolved by Microsoft Support.
      • Use the Outlook.com Help pane (“Help” in the top menu) and the “Still need help?” path to submit a support request, or return to Microsoft account support and reference that unified storage is blocking Outlook.com despite being under quota.

    These steps align with the documented behavior of unified storage and Outlook.com’s send/receive blocking when storage is considered full.

    References:

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