Outlook storage incorrect

Hi!

What is the exact message you are seeing? Please send me a screenshot. Maybe Outlook is saying "From local storage, or from the Inbox that has exceeded its limit, it is necessary to delete or compress the OST file."

If you are receiving a message similar to "Your mailbox has reached its maximum size limit...", you should follow the steps below. If you are receiving another message, please send me a screenshot.

• If your image contains personal information, cross it out.

https://support.microsoft.com/en-us/office/reduce-the-size-of-your-mailbox-and-outlook-data-files-pst-and-ost-e4c6a4f1-d39c-47dc-a4fa-abe96dc8c7ef

• First, see Reduce mailbox size, if that doesn't work, expand and see Reduce the size of a data file....

You can also delete the OST file. Close Outlook > Press Windows + R > type %localappdata%\Microsoft\Outlook > Delete the OST file with your email name. When you delete an OST file, open Outlook and a new OST file will be created.

• If you want to keep this OST file, simply rename it to anything, such as your_email_backup.ost.

The Outlook “storage full” error is controlled by two different quotas that can get out of sync:

1. Microsoft cloud storage (OneDrive + other services)
2. Email (Outlook.com) mailbox storage

The 1 TB shown for Microsoft 365 Personal is the cloud storage quota, not the mailbox quota. Even if only 0.1 GB of the 1 TB is used, Outlook can still block mail if either:

• The Microsoft unified storage quota is marked as exceeded, or
• The email storage quota for the Outlook.com mailbox is exceeded.

When that happens:

• Outlook.com will block sending/receiving mail.
• The error can persist for some time after freeing space or upgrading.

To correct the discrepancy:

1. Check whether “Microsoft Unified Storage is full”
   • If this message appears, it means the cloud storage quota is exceeded, even if the mailbox itself looks fine.
   • In this state, Outlook.com blocks sending and receiving email until the account is back under quota.
2. Get back under the storage quota
   • If using a free account, either:
     • Buy a subscription to increase mailbox quota, or
     • Free up storage space using the storage management tools.
   • If already using Microsoft 365 Personal/Family:
     • Consumer mailbox limits are capped at 100 GB. To restore mail flow, free up mailbox storage (delete mail, empty Junk and Deleted Items) until usage is below the quota.
3. Allow time for quotas to refresh and resync
   • After freeing space or purchasing storage, it can take time for Outlook.com and OneDrive to update and clear the block.
   • If the Outlook app still shows “full” while web storage shows under quota, unlinking and relinking OneDrive or signing out and back into Outlook can help force a refresh.

If the mailbox regularly approaches its limit and more than 100 GB is needed, consider moving to an enterprise plan that supports larger mailboxes.

References:

• Mailbox storage limits in Outlook
• Storage limits in Outlook.com
• Microsoft storage FAQs
• storage exceeded in outlook after purchasing MS 365 subscription - Microsoft Q&A
• How to Fix outlook - Microsoft Q&A
• my outlook email is not delivered - Microsoft Q&A
• Storage showing full - Microsoft Q&A