You need to find out or verify what your IT Management Application Identity (AppID) account is. This is the account that many Altiris services on the Notification Server run as, including:
ITMS 7.5 to 8.1 RU7
There are two ways to verify your current IT Management Application Identity account.
Using the Symantec Management Utility.
In the Symantec Management Console go to Settings|Notification Server|Notification Server Settings
You will find the current Application Identity in the "Account" field, highlighted in orange above. The Application Identity account is presented using the following format: <domain name>\<username>.
Using the Symantec Installation Manager
Launch the Symantec Installation Manager and click on "Configure Settings", then click on "Configure NS Settings" and then on the "Next" button. You will see the following.
You will find the current Application Identity in the "User name" field, highlighted in orange above.
Caution: If you want to change the Application Identity or its password, please see: How to Change the Application Identity Account Password