E-mail after user verification

I have the Pie Register plugin installed and have it set up that after registration admin approval is required to finalize the registration process. An e-mail is sent to the user confirming that they have registered and an e-mail is sent to the admin notifying that a new person has registered and needs to be verified. Now, I would like to know is there a method, maybe through another plugin, to send out an e-mail to the user after the admin has verified him or her without having the admin to manually write and send one out.
Thank you!