How to Find Large Emails in Outlook (Every Version, 2026)
When your Outlook mailbox is nearly full, a handful of emails with big attachments are usually the cause — one 25 MB video or a thread of large PDFs eats more space than thousands of plain-text messages. Finding the largest emails lets you delete or archive them and reclaim storage fast. This guide covers sorting by size, searching by message size, and using Outlook’s built-in cleanup tools across every version.
This guide covers every current version: Outlook on the web, the new Outlook for Windows and Mac, and classic Outlook for Windows.
1. Sort the Folder by Size
The quickest way to see your biggest messages is to reorder a folder by size — see the full sort emails in Outlook guide for all the sort options.
Classic Outlook for Windows:
- Open the folder (start with Inbox, then check Sent Items)
- Go to the View tab → Arrange By → Size
- Outlook groups messages into bands: Huge (1–5 MB), Large (500 KB–1 MB), Medium, Small, Tiny
- The Huge and Large groups at the top are your cleanup targets
Outlook on the web / New Outlook (Windows & Mac):
- Open the folder
- Click the sort control above the message list
- Choose Sort by → Size
- The largest messages move to the top
2. Search by Message Size
Outlook’s search box accepts a size keyword so you can list only messages above a threshold — the most precise method.
All versions (classic, web, new Outlook):
- Click in the Search box at the top
- Type one of these queries:
messagesize:>5 MB— messages larger than 5 MBmessagesize:enormous— messages over 5 MBmessagesize:huge— messages 1–5 MBmessagesize:large— messages 500 KB–1 MB
- Press Enter
- To search your whole mailbox, set the search scope to All folders (classic) or All (web)
You can combine filters, e.g., messagesize:>10 MB hasattachments:yes to find only big messages with attachments.
3. Add a Size Column to the Message List
Seeing the exact size of each message helps you decide what to cut.
Classic Outlook for Windows:
- Right-click the column header bar above the message list
- Choose Field Chooser
- Drag the Size field into the header row
- Click the new Size column header to sort largest-first
If you’re in a compact single-line view, switch to View → Change View → Preview or turn off the reading-pane layout so columns are visible.
4. Use Built-in Mailbox Cleanup Tools
Outlook ships with tools that locate big and old items in one place.
Classic Outlook for Windows — Mailbox Cleanup:
- Go to File → Tools → Mailbox Cleanup (or File → Info → Tools → Mailbox Cleanup)
- Click Find items larger than and enter a size in KB (e.g., 5000 for 5 MB)
- Click Find to list matching messages
- Review the results and delete what you don’t need
- Use Empty Deleted Items folder in the same dialog to reclaim space
Outlook on the web / New Outlook — Storage:
- Click Settings (gear) → General → Storage
- You’ll see a breakdown of which folders use the most space
- Click a folder to clean it, or use the option to permanently delete items older than a chosen age
5. Delete or Archive the Largest Messages — and Reclaim the Space
Finding big emails only frees space once they actually leave the mailbox.
- Select the oversized messages (Ctrl-click for several)
- Delete them, or Archive them to move them out of your primary mailbox — see how to archive emails in Outlook
- Empty the Deleted Items folder: right-click it → Empty Folder (classic) or Empty folder (web). Until you do this, deleted items still count against your quota
- If you only need the message but not the file, open it, save the attachment elsewhere, then remove the attachment from the email (classic Outlook: select the attachment → Remove Attachment)
For bulk removal across a folder, see how to mass delete emails in Outlook.
Quick Reference
| Method | Where | Best for |
|---|---|---|
| Sort by Size | View → Arrange By → Size (classic) / Sort control → Size (web) | Quick visual scan |
messagesize:>5 MB search | Search box, all versions | Precise thresholds |
| Size column | Field Chooser → Size (classic) | Seeing exact sizes |
| Mailbox Cleanup | File → Tools → Mailbox Cleanup (classic) | Guided cleanup |
| Storage breakdown | Settings → General → Storage (web/new) | Per-folder usage |
Troubleshooting
Sorting by size doesn’t show attachment files, only message sizes.
Outlook’s size is the total message size, which includes attachments — a large attachment makes the whole message large. Add the Attachment column (Field Chooser) if you want to spot which messages carry files.
The messagesize search returns nothing even though my mailbox is full.
Your search scope is probably limited to the current folder. Set it to All folders (classic) or All (web), and confirm the syntax has a space: messagesize:>5 MB, not messagesize:>5MB in older builds.
I deleted big emails but my mailbox is still full.
Deleted messages sit in Deleted Items and keep using quota. Right-click Deleted Items → Empty Folder, then check the Recoverable Items area, which can also hold space for up to 14–30 days.
There’s no Mailbox Cleanup tool in new Outlook or on the web.
Mailbox Cleanup is a classic-Outlook feature. On the web/new Outlook, use Settings → General → Storage to see per-folder usage and bulk-delete old items, or use the messagesize search.
My Sent Items folder is the biggest but I never noticed.
Sent mail keeps copies of everything you sent, including the attachments. Sort Sent Items by size too — it’s often the largest single folder. Archive or clear old sent attachments to recover significant space.
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More on Outlook: How to sort emails in Outlook · How to clean up your inbox in Outlook · How to archive emails in Outlook · How to mass delete emails in Outlook · How to filter emails in Outlook · How to create folders in Outlook
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