Why is the initial connection done via SQL authentication ? (4269495)

Why is the initial connection to Quest Archive Manager database done via SQL authentication ?

The issue is cause by a technical limitation called "double hop problem" which is a known problem in Microsoft Windows Authentication. SQL authentication is a workaround for the double-hop authentication issue.

To use Windows Authentication only, a linked server configuration is required.

The windows authentication will only work if the MessageStats Task execution server is installed on the MessageStats database server. The linked server (SQL server management studio) is created on the MessageStats database server. This linked server is originally created with sql authentication. Once the linked server is created (With the archive manager database server name), then you can open the linked server  in sql enterprise Manager or sql server management studio and change it to windows authentication.

Please refer to this Microsoft article for more information about linked servers.
http://msdn.microsoft.com/en-us/library/ff772782.aspx