Please clarify what you are asking. I am not fully understanding what you are describing. As I read it, when the tester assigns the defect to the developer, the developer is getting a notification of the assignment, but I am not fully understanding the second part. The tester clicks submit and the automail is not being delivered. When is this submit being clicked and for what reason (during the defect update, logging of new defect, etc ). It is not clear what is not working in the second part of your described issue.