BYOIDP - Mendix Cloud SSO - not using email for username

Going through the configuration steps of Single Sign On with Mendix Cloud and our company IDP, I ran into a question on step 4. Step 4 is configure claim mapping. Mendix automatically selects email for the user name mapping, however I want to use something else.   My question is if I use something else what happens to the accounts that have already been setup using their email?   From the documentation Set Up an SSO (BYOIDP) | Mendix Documentation – “The user’s email address is used to associate a user’s existing account within Mendix with the user’s account at your IdP. This means that any existing Mendix account is linked to their IdP account for authentication, rather than a new Mendix account being created for them.”   That sounds all good in theory, but when I decided to use the test link they provide It would force me to create a new account. I didn’t complete this new account creation process for fear of messing up my account and then trying to figure out how to fix. 
1 answers

Hi Peter,

if you use 'something else' and the Mendix platform cannot find an existing account for the value that was received - it assumes it's a sign-on for a yet non-existing account and indeed redirects the process into a platform signup.

I'm not sure how you would envision a different kind of logic?