play a sound when i receive an email

Well anytime you get an email, you should be getting a notification with a sound. If you want a specific sound for a specific person, Android itself cannot do that. Only an app that uses email would be able to configure that.

 

If you assign a label to a certain contact in gmail, you can get the app to play a different notification each time that label receives an email.

Open the gmail app, hit menu, more, settings, your email name, labels to notify. This will allow you to assign a specific ringtone to a specific label.

 

You need to tell the app to sync that label. Open the gmail app, hit menu, more, settings, your email name, Sync inboxes and labels, select your label and that will appear in the "labels to notify" menu I mentioned above.

Sorry, I have all labels synced and forgot that you need to set them up that way before you could assign them a specific tone.