Who's to say that they'll like to use 4 digits maybe they'd like to use their whole date of birth like Simon250712 or two digits for the year of birth or an age like Simon12, there's no telling what username that potential members might like, so i'd have to say it's pretty much impossible to do what you suggest unless you want to alienate people before they join :)

Does it work on 4.1.10 ?

As it says in the description if your installation has the hook userdata_presave then yes it should (and vb4 series DOES have it :))

Thank you Simon. Always nice to have another 'simple' spam prevention tool in our forums 'tool kit'. Installed and rated excellent.

You're very welcome.