I doesn't have an idea to answer it, but when i seacrhing for the answer i've found the way to solve this problem. I really hope this can solve this problem. Try using http://www.spypig.com

I didn't try it yet..

Haven't tried it yet but plan to do so when time permits.

Thanks!

Apparently Spypig requires the use of HTML email by both the sender and recipient, however. I read my email as text only, and many other people do the same. You could set the email application to set up the message to return a receipt if opened. Of course, there is a setting in an email client that can prevent the return of receipts, so that is not foolproof either.