Confirmation emails not being sent

Hi there,

I was previously using the WP Subscribe widget and it was working fine; but i did not like how clunky it looked. So I have just installed the "Subscribe by Email" plugin and all the settings seem to be in order.
From the settings page, I have tried the "send a test email" and it works - i receive a dummy email.

However, when i go to my actual website as a user and enter the same email to subscribe; nothing is sent out.

Can you please help what i could be missing?

Cheers,
Arief