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Bryz︱🦾
Bryz︱🦾

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📬 "My Mailbox Is Full!" Find What's Eating the Space Before You Delete Anything

#itsupport #microsoft365 #outlook #beginners

"I can't send email. Outlook says my mailbox is full!" 😩

It's one of the most common help desk tickets out there. The lazy fix is "just delete some old stuff." The better fix takes five minutes and actually solves it. Let's go. 🚀

🔍 Step 1: Find the real space hog

Don't guess. Measure.

In classic Outlook for Windows:

  1. Right-click your mailbox name in the folder pane.
  2. Choose Data File Properties.
  3. Click Folder Size.

You'll see every folder and how big it is. Usually one or two folders (Sent Items, Deleted Items, or an old project folder) are doing all the damage.

If you're the admin, you can check from Exchange Online PowerShell:

Connect-ExchangeOnline
Get-EXOMailboxStatistics -Identity user@contoso.com | Select-Object DisplayName, TotalItemSize, ItemCount
Get-EXOMailboxFolderStatistics -Identity user@contoso.com | Select-Object Name, FolderSize, ItemsInFolder
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📎 Step 2: Go after the big stuff

  1. Empty Deleted Items first (right-click > Empty Folder).
  2. Open your biggest folders and sort by Size.
  3. Delete or save off the giant attachments you don't need anymore.

A handful of old emails with huge attachments can free up gigabytes. Deleting 2,000 tiny newsletters barely moves the needle. 💡

🗑️ Step 3: Don't forget Recoverable Items

Here's the one most people miss. Mail you "permanently" delete can still sit in the Recoverable Items folder, and in many setups that space still counts against you.

In classic Outlook:

  1. Select Deleted Items.
  2. Click Recover Deleted Items (Folder tab or the link at the top).
  3. Select what you don't need and choose Purge.

Note: if the mailbox is on a litigation hold or retention policy, items may not purge. That's by design, so loop in your admin.

📦 Step 4: Stop it from coming back

Cleaning up once is nice. Never getting the ticket again is better. ✅

  • Turn on the online archive so older mail moves out of the main mailbox.
  • Apply an archive policy that moves mail after a set number of years.

Admins can enable the archive like this:

Enable-Mailbox -Identity user@contoso.com -Archive
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🧠 The takeaway

Measure first, delete the big stuff, purge Recoverable Items, then set up an archive. That's a fix the user won't have to call you about next month. 🙌

What's the biggest mailbox you've ever had to clean up? Drop it in the comments 👇

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