Want to check email already exists or not before verifying email in signup of Azure AD B2C flow.

I'm working on a custom sign-up flow in Azure AD B2C, and I want to include a step to check whether an email address already exists before initiating the email verification process. The goal is to enhance the user experience by avoiding unnecessary verification for existing email addresses.

I'm looking for guidance on how to configure a custom user journey that incorporates a technical profile specifically designed to validate the uniqueness of the provided email address. Ideally, I want to collect the user's email, check if it exists, and then proceed with email verification only if the email is new.

If anyone has experience implementing such a scenario or can provide insights into the necessary steps and configurations, I would greatly appreciate your assistance. Additionally, any code snippets or examples related to this specific use case would be extremely helpful.

Thank you in advance for your support!