You should not think in disable that function because your server can't send e-mail. Today email delivery is pretty cheap and is easy as create a mandrill account. https://mandrillapp.com that will be free for the first 12.000 emails that you send per month, and then it will cost almost nothing to send more.
i know it cheap, but i want user easy to upload, just click login with facebook and then upload, don't need waiting to active account :s it difficult with some normal user