Since July, my email stop working, my setup is very simple (I am not very knowledgeable about WP), is a turnkey linux WP setup, for an intranet (not public site) since I notice of this issue with the email I started looking for options and pretty much every link point to WP mail SMTP, however because my site is not public I cannot continue with that path because for the Gmail email setup it requires the authorized domain that I does not have.

However prior to July I didn’t have that problem using the built in email sender in WP.

I want to known if it is because an update in the core, and if it can be solved.

Regards.

Another alternative is that PHP’s mail() function is still active, but spammer activity from the server has already caused any email sent from it to be blacklisted. This would result in the emails being sent, but never received by any email address with basic anti-spam capabilities.

You can check this by leaving a comment on your site and checking if you receive an email. Another alternative would be to use the Health Check plugin and sending yourself a test email from the plugin’s Tools tab to see if it works.

If you didn’t receive a test email, you could try using an SMTP plugin to configure your WordPress site to use your email’s outgoing mail server instead of PHP’s mail() function.