"Either there is no default mail client or the current mail client cannot fulfill the messaging request" error message when you send e-mail from third-party program in Outlook (813745)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you try to send an e-mail message from a third-party program, such as a Usenet newsreader, you may receive the following error message:

Either there is no default mail client or the current mail client cannot fulfill the messaging request. Please run Microsoft Outlook and set it as the default mail client.

CAUSE

This issue may occur if the Outlook registry key is corrupted. When other programs try to use the Outlook Simple MAPI interface, they cannot retrieve the required information from the registry.

RESOLUTION

To resolve this issue, you must first remove the corrupted Outlook registry key, and then perform a Detect and Repair operation to have Outlook rebuild the key. To do this, follow these steps.WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

Click Start, and then click Run.
In the Open box, type regedit, and then press ENTER.
In Registry Editor, locate the following subkey in the registry: HKEY_LOCAL_MACHINE\Software\Clients\Mail\Microsoft Outlook
Select the subkey, and then press DELETE.
Click Yes.
Quit Registry Editor.
Start Outlook.
On the Help menu, click Detect and Repair.
Follow the instructions on the screen to complete the repair.