Is GameSparks planning on adding E-mail authentication anytime soon ? I'm currently evaluating both PlayFab and GameSparks and one thing that does appeal with PlayFab is having the option for a player to create an account using an e-mail address. I know GameSparks lets a player create a user name and password but if the player forgets their password and then buys a new device and wants to login to their games, then there's no way to retrieve it. E-mail login is much easier in that respect. GameSparks would also have to send an e-mail to a new account user asking them to confirm the e-mail address so they don't just sign up with any old e-mail, but I think this would be a great addition. Now that Microsoft has acquired PlayFab, I think it's important that GameSparks listens to what users want and competes. Thanks!
Gamesparks has native integration with SendGrid so it's pretty darn easy to set that up yourself, since as you already recognized, user authentication is just a superset of email authentication. This allows you to set up whatever restrictions you want for the registration.
For instance, I've set it up to call a zerobounce API to verify the email address is authentic (it hits the email registrars servers), but you could do like you say and send an actual email for complete verification.
The code to setup password reset with token in email is pretty basic and Gamesparks even shows an example of how to implement in their docs.
As Ryan mentioned we do have guides on how to achieve this in Cloud Code. You can find an example on the old api here and one for the new Game Data Service api here. If you have issues implementing either please get in touch. We'll be more than happy to help. As for providing this as a feature ? It's something we may consider going forward.