Specific alerts on Blackberry Z10: Silent for most, noise for one email address?

Hi Folks.
Recently our work phones have been upgraded to Z10's, however the more complex operating system and notification settings have got us all perplexed.
Naturally we have our phones synced to our works email accounts.
For on-call purposes we need the phones to stay silent for all commnications with the exception of any emails from one particular address.

Currently we have a Contact Notification set up for the email address in question, and also a Level 1 notification set up. However we cannot seem to make the Z10's go off consistantly, every time an email from that address drops in. Are we missing anything, is there another seeting somewhere that needs to be enabled? This is quite serious as emails at night are being missed that really need to be looked at.