When you've got a Drupal-based developer portal, you may wish to enable validation of the user registration data.
One easy thing to do is enable recaptcha in the registration form. There's a quick article here covering an issue with that.
Beyond that, you might want to validate the user name, the email address, and maybe check the email against a whitelist or blacklist.
To help with that, I've produced a small custom module. It allows you to administratively set up validation rules from a fixed set.
To use it, just push it to your devportal repo, then enable it, then configure the settings.
The code is all open source of course, so you can extend or modify it to meet your needs.
Good luck!