Is there a way for us to  turn the attribute Email from the Entity User into a unique value? without the need to create a new user table?

Thank you

Norman In

No. Outsystems doesn't allow system espaces to be edited, only cloned.

The simple solution is to create a new page for user creation so that by default, you don't allow to add repeated emails.

Hello norman,

As Márcio said, it is not possible to change System Entities.

If you are concerned with users created programmatically, one approach is to create a module with wrappers (public Server Actions) for the Users entity, that when creating or updating records in the Users entity, check if the email already exists and throw an exception if the email already exists. Then enforce a policy to use these wrappers instead of the Users Entity Actions. 

But if you use the Users application to create users, then you have to create a new Front End application to deal with users and enforce this there, as Márcio told.