Problem with notification emails when a user receives a message.

I have a problem, it no longer sends me notification emails when a user receives a message.

I don’t understand if it’s a problem with the plugin or my wordpress (I write this because I don’t receive notifications of new messages received from the Front End plug-in and I don’t even receive the email when a user registers on my site).

I also tried to install the WP MAIL SMTP plugin, but I don’t receive them anyway.

It happened from one day to the next without me having made changes.