Hi Sunil,
Thank you for writing to us.
When a new user registers and mails are not received by the admin,
a) Click on RegistrationMagic
b) Click on global settings
c) Go to email notifications
d) Enable: notify site admin and define recipients manually
e) Click on save.
The content of the mail can be changed from RegistrationMagic dashboard > email templates > new submission email body(Add the content here) > save.
The content sent to the user can also be changed by following the same steps. Clicking on RegistrationMagic dashboard > email templates > new user email body. Add the content you want to send to the newly created user > Save
Let us know if the issue still persist and please raise a support ticket on : https://registrationmagic.com/help-support/
Let us know if you have any other questions.
Thank you.