MyBB Email setting for activation (New user)

Hello

I have installed MyBB as when i use Couldflare to secure my sites IP when a new user register with Disposable Emails they can see the servers IP. How can i block that or use email service from NameCheap or a way to hide the IP from Users. I kinda of think that MyBB has it's own email service in which it sends the IP of the server where its installed. Can you guys help me out.

Thanks