Sign up Confirmation email not sent

Hello friends,
Recently, I installed wordpress into my site https://www.a-kamel.com,
every user signup into my site, should has a confirmation link or creating own password link to his email, but …. there is no email sent to him, while if he requested a new password reset he will get an email sent to him.
So what is really this problem ??? every thing works fine into my hosting and my site, just this problem facing me ?? ?? …. So please HELP me to solve it.

You can use this link to try to register and you will see that confirmation message not sent:
https://www.a-kamel.com/wp-login.php?action=register

Also you can try lostpassword reset, you will see that email sent successfully:
https://www.a-kamel.com/wp-login.php?action=lostpassword

Please HELP me.