i couldnt find in the documentation wether there is a way for a tester in a sandbox environment to receive a email reciept from an in app purchase or not . is this a feature ?
No, there is no confirmation email sent by the sandbox system.
It's by design, vs. a bug, if that's what you're wondering - is there a specific reason you're asking?
You'd need to DIY your own background notification scheme if this is a process requirement, otherwise.