Auto User Registration Process

Hello,

I have been thinking to have the following function in my site (any site):

1. User submits his/her application for membership;
2. User receives email confirming the application is received;
3. Site admin receives email of the application;
4. Site admin approves or rejects the application:
4.1 If reject, user receives rejection email;
4.2 If approves, user receives email that contains a link

In step 4, either way requires the ability to send out a customized email.

If anyone happens to come across the similar function/plugin, ideally free but willing to pay here.

Thank you very much.

To forum moderator: if you think there is a better place for this question, please feel free to move it to there and notify me, thank you.