Why does the client not receive any notice to verify their email address?

Hi,

The message should show on the page after registration. If you are having trouble with it, In the plugin’s settings General tab Enable the Redirects to a custom URL if an unverified user tries to login option.

You can also use the shortcode

 [alg_wc_ev_verification_status]

to show the verification notice on other pages.

If the messages are being sent to spam, you need to check with your hosting provider. Most likely SPF or DKIM records might not be set up correctly.