Hi Raj,
As far as I understand, you run a project with several (8-10) test items, right? In this case, the OnStopTest event rises each time when the test item is stopped. That's why, TestComplete sends several messages via e-mail.
To send only one message via e-mail, you need to specify appropriate code (that sends test results) only once in the project, for example, in the last test item.
So, to solve this problem, I recommend that you do the following:
1. Create a new script routine (for instance, SendingResults).
2. Copy the text from the OnStopTest event handler and paste it to the SendingResults routine.
3. Remove the OnStopTest event handler from your project.
4. Add the SendingResults routine to the project test items and make sure that this item is specified at the end of the Test Items list. This will guarantee that the SendingResults routine is executed only once (at the end of the project execution) and thus the test results are send only once.
I hope, this information helps :)