Validate mail in Verification code button

[raokv12]

Hi, In sign up page need to validate the entered mail id already a user in the azure directory, if email exists need to show the message like user already exists if not verification code is to sent to the mail box. I have tried many ways but nothing worked. I need to achieve this by user journey or suggest me the any other way to optain the above request.( With and without user journey)