@jptravelers Could you send me a few examples of the email addresses that didn't receive any notification emails, via this contact form?
@hamedharry Your Jetpack subscribers won't be listed in Users > All Users in your dashboard, and cannot be added through that method either: they will have to submit their email address via the Subscriptions widget.
I tested the widget, and it seems to work correctly; you can now see my email address in your subscriber list.
I also check the Pending subscriptions for your site: the confirmation emails were all sent correctly, and their email provider confirmed reception of the email. The last person who attempted to subscribe to your site received the confirmation email yesterday, at 23:19:24 UTC. Could you ask them to check their Spam / Junk folder, as WordPress.com emails can get caught in them sometimes?