This article explains why an action that calls the following API will successfully set the custom "email" claim for some applications but fail to set it for others.

api.accessToken.setCustomClaim("email", "some@email.com")

• Application with Resource Owner Password Grant (ROPG)
• Access Token
• Custom Claims

The "email" custom claim is configurable only when using an interactive flow that redirects the user to the Auth0 Universal Login for credentials.

When the application uses the password grant, general restrictions apply to "email" as a custom claim. For more details, refer to the documentation on non-restricted claims.

As a workaround, we suggest using a namespaced custom claim and refactoring the application to parse the namespaced claim. 

Related References

• Refer to the documentation on Namespaced guidelines for additional details.