The primary reason for this issue lies in the way Outlook handles Send As permissions. When you send an email using a different account's email address, Outlook checks if the recipient has granted permission for Send As on the sender's account. If permission is not present or is revoked, the error m

How do I fix: Disabling Cached Exchange Mode?

Step 1: Open Outlook and go to File > Options > Advanced.Step 2: In the Advanced tab, click on 'Exchange' and make sure 'Cached Exchange Mode' is disabled. This will force Outlook to refresh its data from the server.Step 3: Restart Outlook to ensure the changes take effect.Step 4: Try sending an ema

Software⏱️ 3 min read📅 2026-06-15

How to Fix: Sending on behalf of a user in Outlook fails with permissions error

Q: Step-by-Step Verified Fixes Clearing Offline Address Books?

Step 1: Locate the C:\Users\username\AppData\Local\Microsoft\Outlook\Offline Address Books folder and delete it. This will reset Outlook's offline address book, which may resolve the issue.Step 2: Restart Outlook to ensure the changes take effect.Step 3: Try sending an email using the different acco

Outlook sending on behalf permission error in Exchange 2010

Quick Answer: Try deleting the address from the From field, redownloading the GAL, or clearing the Offline Address Books folder. If issues persist, consider disabling Cached Exchange Mode.

📋 Table of Contents

⚠️ Common Causes
🛠️ Step-by-Step Verified Fixes
✨ Wrapping Up

Sending on behalf of another user in Outlook can be frustrating when you encounter permissions errors. This issue affects users who have been granted Full Access and Send As permissions in Exchange 2010, yet still face difficulties sending emails using a different account's email address.

Dealing with this error requires patience and persistence, as the solution may involve multiple steps and possible workarounds.

⚠️ Common Causes

The primary reason for this issue lies in the way Outlook handles Send As permissions. When you send an email using a different account's email address, Outlook checks if the recipient has granted permission for Send As on the sender's account. If permission is not present or is revoked, the error message appears.
Another possible cause could be related to cached data or offline address books. In some cases, deleting these files or resetting Cached Exchange Mode can resolve the issue temporarily.

🛠️ Step-by-Step Verified Fixes

Clearing Offline Address Books

Step 1: Locate the C:\Users\username\AppData\Local\Microsoft\Outlook\Offline Address Books folder and delete it. This will reset Outlook's offline address book, which may resolve the issue.
Step 2: Restart Outlook to ensure the changes take effect.
Step 3: Try sending an email using the different account's email address again to see if the issue persists.

Disabling Cached Exchange Mode

Step 1: Open Outlook and go to File > Options > Advanced.
Step 2: In the Advanced tab, click on 'Exchange' and make sure 'Cached Exchange Mode' is disabled. This will force Outlook to refresh its data from the server.
Step 3: Restart Outlook to ensure the changes take effect.
Step 4: Try sending an email using the different account's email address again to see if the issue persists.

✨ Wrapping Up

To resolve the sending on behalf of another user in Outlook permissions error, try clearing the Offline Address Books or disabling Cached Exchange Mode. If these methods do not work, you may need to contact your helpdesk for further assistance.

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