Drupal-User-Registration-Validation
This module validates information submitted on the user registration form. There are some hard-coded checks:
- disallow spaces in usernames
- disallow non-word characters and spaces in usernames
- disallow non-word characters in firstnames
- disallow non-word characters in lastnames
- apply a blacklist: disallow specific email domains (admin specifies)
- apply a whitelist: allow registration only from specific email domains (admin specifies)
To configure how the validation is done, there is an Administrative configuration panel under Admin > Config > People > User Registration Validation
It looks like this:
Modifying the checks
If you'd like to modify the checks, you can look in functions.inc for the dpchiesa_validate_userreg_available_checks
function. Add or remove checks there, following the pattern. You should be able to figure it out.