Connecting to SQL Server by Using SQL Server Agent Service
The SQL Server Agent service can connect to a local instance of SQL Server by using either Windows Authentication or SQL Server Authentication. Whichever method you select, the account must be a member of the sysadmin fixed server role.
SQL Server Agent can use two different authentication methods to connect to a SQL Server instance:
Windows Authentication forces the SQL Server Agent service to connect to an instance of SQL Server by using the Microsoft Windows domain account that you defined as the service startup account.
SQL Server Authentication forces the SQL Server Agent service to connect to an instance of SQL Server by using a SQL Server authenticated login. Only logins that are members of the sysadmin role are available.
Beginning with SQL Server 2005, SQL Server Agent does not support SQL Server Authentication. This option is available only when you administer an earlier version of SQL Server.
For more information about setting up the SQL Server connection, see How to: Set the SQL Server Connection (SQL Server Management Studio).