Users don't receive confirmation email after signing up

Hi. On my website, I was modifying some things in my sign up form and everything was going smooth, I created an account for testing the form and it was fine, I received a confirmation email. But after some more modifying, when I wanted to create an account, I didn’t receive the confirmation email. I use the default WordPress sign up form together with Register plus Redux because I wanted the “choose password” field, which wasn’t present in the default WordPress sign up form.

I may have modified by mistake one of the following files. I really don’t understand what I could erase for the users to not receive confirmation emails:

wp-signup.php
wp-login.php
register-plus-redux.php
rpr-activate.php
rpr-login.php
rpr-new-user-notification.php
rpr-signup.php

The thing is that the sign up form works for sure, because when I check my users page, the new user appears, and it’s “unverified”, awaiting approval. So the issue must be somewhere in a code related to the email confirmation.