so I take this as impossible to do?

Out of the blue ... if you're using for e.g. Exchange you would need to create at least some kind of address-book entry with this mail-address. The easiest way to accomplish this would be to create a user with this address. This way clients (like outlook) would show the realname based on the addressbook-entry instead of the mail-address.

This is just a random thought - I haven't tried this though.