I have to admit I found the very concept of using a value that could change as a primary repulsive from an aesthetic point of view. It's just bad database design.
Still, I feel for you. My primary concern, though, was that it made life more complicated for me. But email adresses were separate from ERP user names, and we did not have two employees with the same name, so [email protected] was good enough for our purposes.
As someone with a common first name and common surname, this drives me bananas.
I still get emails from my graduate university to email: [email protected] meant for some undergraduate in a sea of 50k students, and have to reply that I've had that email for 20 years and they have the wrong person with a very common name.