IAlertNotifyHandler implementation I need name of the user who created/add the current item/document to the list (for which this alert is being sent). What is the way to do this?
When you create your OnNotification method you can access the list item with code similar to this.
Not sure on your requirements but you may need to add some additional code to then get a domain\username if this is what you require.
Note: This is sub-optimal code to highlight only the code needed to get the list item. I know there are dispose issues here.
No Need for Code or anything, Add the Fields Created By and Modified By and you see all.