This error occures when a End-user is using outlook when reciving their digest. The End user clicks on the link to release the message and they get the following error message: 

General Failure. The URL was: https://us1.proofpointessentials.com/app/release.php?r=xxxxx...*. Application not found

PC World Author Rick Broida found the solution talking to a Microsoft Repesentive about this issue "the problem arises when various applications corrupt the default http:// protocol handler registration. Thus, fixing it is fairly easy."

Steps to fix this issue: 

1. Click on Start > Then click on Control Panel 
2. Click on Program > Then click on Default Programs > then Click on Set your default programs
3. Find the browser you prefer to use. > Click on Set this program as default
4. Click on Ok and your done

Note: It is recomended not required to restart your computer after this change. 

Used Source:

Broida, Rick. "Microsoft's Fix for Outlook's 'General Failure' Error for E-Mail Links." PCWorld. PCWorld, 05 Dec. 2011. Web. 14 Aug. 2015.

Other External Links:

"Fix General Failure When Open Link or URL from Outlook and Windows Mail  Raymond.CC." RaymondCC Blog. N.p., 25 Mar. 2008. Web. 14 Aug. 2015.

Srinivasan, Ramesh. "Fix for Application Not Found Error When Opening a Hyperlink or URL - The Winhelponline Blog." Winhelponline Blog RSS. N.p., 30 May 2008. Web. 14 Aug. 2015.