You may need to find emails with large attachments to manage your mailbox size or locate specific files. Outlook’s Search Folders can automatically filter your mail based on custom criteria. This article explains how to build a Search Folder that finds all messages with attachments larger than 5 megabytes.
Key Takeaways: Creating a Search Folder for Large Attachments
- Folder > New Search Folder > Create a custom Search Folder: Opens the dialog to define specific filter rules for your new virtual folder.
- Criteria > More Choices > Size (kilobytes): Allows you to set a minimum size filter for messages, which includes their attachments.
- Search Folder Properties > Browse: Lets you select which mail folders the Search Folder will scan, such as your entire mailbox or specific subfolders.
Understanding Outlook Search Folders
A Search Folder is a virtual folder that displays a dynamic view of emails matching specific rules. It does not move or copy messages. Instead, it provides a live, filtered look at your mailbox. This feature is available in Outlook for Microsoft 365 and Outlook 2021 connected to Microsoft Exchange or POP/IMAP accounts. The search runs against your local mailbox data, so it requires cached or offline mode for Exchange accounts to work reliably with custom size filters.
How Size Filtering Works
The size condition in a Search Folder checks the total size of the email item. This includes the message header, body, and all attached files combined. When you set a criterion for “size greater than 5120 kilobytes,” you are filtering for emails where the total item size exceeds 5 MB. This effectively finds messages with large attachments, as the text of an email is typically only a few kilobytes.
Steps to Create the Large Attachment Search Folder
Follow these steps to create a Search Folder that continuously shows emails with attachments over 5 MB.
- Navigate to the New Search Folder dialog
In the Outlook ribbon, click the Folder tab. In the New group, click New Search Folder. - Select the custom Search Folder option
In the New Search Folder dialog box, scroll to the bottom of the list. Select Create a custom Search Folder, then click Choose. - Name your Search Folder
In the Custom Search Folder dialog, type a name into the Name field. Use a clear name like “Attachments Over 5 MB.” - Click the Criteria button
This opens the Search Folder Criteria dialog where you will define the filter rules. - Go to the More Choices tab
In the Search Folder Criteria dialog, click the More Choices tab. - Set the size condition
Check the box next to Size (kilobytes). From the dropdown menu next to it, select greater than. In the number field, enter 5120. This value represents 5 MB in kilobytes. - Add the attachment condition
While still in the More Choices tab, check the box next to Only items that have one or more attachments. This ensures the results are only emails with files attached. - Select the folders to search
Click the Browse button. In the Select Folder(s) dialog, check the box for your main mailbox or specific folders you want to include. Click OK to confirm your selection. - Apply and create the folder
Click OK in the Search Folder Criteria dialog. Click OK again in the Custom Search Folder dialog. The new Search Folder will appear in your Folder Pane under Search Folders.
Common Mistakes and Limitations
Search Folder Shows No Results
If your new folder is empty, first verify you have emails meeting the criteria. The size filter applies to the total email item. An email with a 4.9 MB attachment might be just under 5 MB total. Try increasing the size value slightly, like to 5200 kilobytes. Also, confirm you selected the correct mail folders in the Browse step. The Search Folder only scans the folders you explicitly chose.
Search Folder Performance is Slow
Search Folders that scan your entire mailbox, especially with complex rules, can update slowly. To improve performance, limit the scope in the Browse step to specific subfolders instead of your entire mailbox. Also, ensure your Outlook data file is not excessively large and is regularly compacted.
Size Filter Uses Kilobytes, Not Megabytes
A frequent error is entering 5 in the size field, thinking it is megabytes. The dialog uses kilobytes. You must convert megabytes to kilobytes by multiplying by 1024. For 5 MB, you enter 5120. For 10 MB, you would enter 10240.
Search Folder vs Manual Search: Key Differences
| Item | Search Folder | Instant Search (Ctrl+E) |
|---|---|---|
| Purpose | Persistent, saved view of emails matching rules | Temporary, one-time query in the current folder |
| Update Behavior | Updates automatically as new mail arrives or items change | Static results from the moment you run the search |
| Query Complexity | Supports multiple combined criteria like size and attachments | Best for simple keyword or sender searches |
| Access | Permanent folder in the navigation pane | Requires re-typing the search query each time |
| Scope | Can be configured to search multiple folders at once | Typically searches only the selected folder by default |
You can now efficiently monitor emails with large attachments using a dedicated Search Folder. This helps manage your mailbox quota and find specific files quickly. For another useful filter, try creating a Search Folder for all unread messages from a specific sender. Remember that you can modify any Search Folder’s criteria later by right-clicking it and selecting Customize this Search Folder.