Activation Email not received

Hello, I′ve already used this plugin in many websites and didn′t have any problem.
I installed it in a new one and the problem is that the user don′t receive the email confirmation with the link to activate account.
(Same hosting and same STMP plugin and configuration as always) maybe the problem is with the wordpress version?

pd: new account email to admin, and password reset to user are send correctly

I hope could help me
Thanks