How to Search Outlook for Emails Sent on Behalf of Another User

When a delegate sends an email on behalf of a manager or colleague, Outlook marks the message with a specific header. Standard search using sender names often fails to locate these emails because the From field displays the manager’s name, not the delegate’s. This article explains the underlying mechanism that stores the delegate’s identity in the Sent Representing field. You will learn how to construct the correct search query using Outlook’s Advanced Find tool to reliably find all messages sent on behalf of another user.

Why Standard Search Misses Emails Sent on Behalf of Another User

When you search for emails by sender, Outlook looks at the From field. In a send-on-behalf scenario, the From field shows the mailbox owner, not the delegate. For example, a delegate named Jane sends an email on behalf of her manager Mark. The From field displays Mark’s name and email. A search for Jane will not return that message.

Exchange and Outlook store the delegate’s identity in a separate message property called Sent Representing. This property is not visible in the message list or reading pane. The Sent Representing field contains the email address of the user who actually sent the message. To find these emails, you must query this hidden property.

Steps to Search for Emails Sent on Behalf of Another User

You have two methods to perform this search. Method 1 uses Advanced Find with a specific field. Method 2 uses Instant Search with a keyword syntax. Both methods require you to know the delegate’s email address.

Method 1: Using Advanced Find

1. Open Advanced Find
   In Outlook, press Ctrl+Shift+F on your keyboard. The Advanced Find dialog box appears.
2. Switch to the Advanced tab
   Click the Advanced tab at the top of the Advanced Find dialog. This tab lets you build custom search queries.
3. Define the field
   Click the Field button. A drop-down menu appears. Go to Frequently-used fields and select Sent Representing. If you do not see Sent Representing in that list, click All Mail fields and scroll to find Sent Representing.
4. Set the condition
   In the Condition drop-down, select is (exactly). In the Value box, type the delegate’s full email address, for example jane@contoso.com.
5. Add the condition
   Click Add to List. The condition appears in the query list below.
6. Run the search
   Click Find Now. Outlook searches the current folder and displays all messages sent on behalf of another user by that delegate. To search all folders, change the Look drop-down at the top of the dialog to All Mail Items.

Method 2: Using Instant Search

1. Enable Instant Search
   Click the search box in the current folder. The Search tab appears on the ribbon.
2. Type the search keyword
   In the search box, type the following syntax exactly:
   sentrepresenting:delegate@domain.com
   Replace delegate@domain.com with the delegate’s actual email address. Do not include any extra spaces.
3. Press Enter
   Outlook filters the current folder to show only messages where the Sent Representing property matches the delegate address.
4. Scope the search
   To search all mailboxes, click the Search tab and then click All Mailboxes. This option is available only in Outlook with Exchange accounts.

If the Search Returns No Results or Incorrect Results

Advanced Find shows no messages even though I know they exist

The Sent Representing field is not indexed in some Outlook configurations. If your search returns zero results, rebuild the search index. Go to File > Options > Search > Indexing Options. Click Advanced, then click Rebuild. This forces Windows Search to reindex all Outlook items. After the index rebuilds, repeat the search.

Instant Search does not recognize the keyword sentrepresenting

Instant Search keyword syntax requires the property name to match the exact Exchange attribute name. If sentrepresenting does not work, try the alternative syntax from:delegate@domain.com combined with a folder filter. This method is less precise because it matches any message from that address, not just send-on-behalf messages. For accurate results, use Advanced Find instead.

I need to find all messages sent by any delegate, not a specific one

Outlook does not support a wildcard query for the Sent Representing field. You must run separate searches for each delegate. To find all messages where the Sent Representing field exists, use the condition Sent Representing is not empty in Advanced Find. The Condition drop-down includes an option called is not empty. This returns every message sent by any delegate, but the list may be large in a busy mailbox.

Advanced Find vs Instant Search: Key Differences for Send-on-Behalf Queries

Item	Advanced Find	Instant Search
Access method	Ctrl+Shift+F or Search Tools > Advanced Find	Click the search box or press Ctrl+E
Field selection	Explicitly choose Sent Representing from a list	Type the keyword sentrepresenting manually
Wildcard support	Supports is not empty condition	No wildcard support
Search scope	Single folder or all mail items	Current folder only unless you click All Mailboxes
Index dependency	Requires indexed Sent Representing field	Requires indexed Sent Representing field

Advanced Find is the more reliable method because it lets you verify the field name and condition. Instant Search is faster for repeat searches once you confirm the keyword works in your Outlook environment.

You can now locate any email sent on behalf of another user by querying the Sent Representing property. Use Advanced Find for the most accurate results, especially if you need to search across multiple folders. After you confirm the delegate’s email address, save the search as a Search Folder for quick reuse. To create a Search Folder, go to Folder > New Search Folder > Create a custom Search Folder and paste the Advanced Find criteria into the search folder definition.