I didn't get too many emails from PCS during my build tbh. You should be emailed when your rig changes 'status' (ie goes from building to testing etc.) but sometimes depending on how fast it is this may not happen. You can always log into your account (on the main site not the forums) and check on the status of your build there . Try not to hit the refresh button too hard haha.
I'm assuming I'll get ones as it progresses.