[TYPO3] suggestions on custom registration in typo3

[Denis Shapovalov]

Hi,

I'm kind of Typo3 newbie, this is my only 2 project with it.
Facing a project and i'm really doubt if i should take it. 

Hope that here, more experienced developers can suggest me some same ideas and somehow clarify difficulties (or maybe simplicities!) i may run at.

This should be a protecterd site, users should register before accessing it.

Registration process is simmiliar to that on many forums, i.e. with confirm email letter sent to user. But it is tricky at the same time, because users trying to register should be diveded by their email addresses. 

If the user has email from "partner" domain, i.e. name at ourpartner.com
he/she should *automatically* recieve registration confirmation.

But if the user is not from "partner", i.e. his/her email is name at anything.com
 the request for registration should be approved by an employee manually, who will decide if this person is allowed to register and send an apropriate answer with link to complete registration or refusal.

Sorry to say but i have no experience or idea how to implement this custom feature in Typo3, and how much time and work it will take.

Surely i can create a separate server script that handle validation of user's emails, but i don't know how to make this talk to Typo3 engine.

After all, is my fear for not managing well-taken? 
Thanks!

Greetings,
Denis