What features in Genesys Cloud CX require a valid email address? 

Does a list of this feature exist? 

That gets a bit granular really but at a high level unless you're using SSO you can technically use any email address as the user's login.  But keep in mind anything that Genesys needs to email out (password reset links, scheduled reports, voicemail notifications etc) will fail.  This ultimately comes down to your InfoSec requirements really.

What is it you're trying to achieve?

Vaun, our end client has asked for the granularity you suggested. 

Client will be using SSO. 

Agents will be using SSO.

Agents use employee ids to login today and do not have email. Client does not want to issue email addresses just for Genesys Cloud.

We are talking about 5000+ agents they do not want to give email addresses. They are not using Genesys Cloud VM. 

This brings me back to the features that require a valid email address.