I am looking for something between 50 and 500 
As I said, my api is written by php.
I have an application and my forum is linked to user profile in my application. Users can change their email within my application and I want to automatically change discourse user email too.
Sorry I dont know what is IdP but as for SSO, since I already have a large userbase, implementing an sso for my discourse would break current users account and they need to verify themselves again. I don’t like that. And my problem would be fixed as easily as being able to change email without confirmation with an API call.