Web to Lead form validation

Hi, I hope I'm not missing something obvious but I can't see a way to validate data being entered on the CRM web to lead form.

For instance, if you have a field in your leads table called 'event date' that is mandatory, and you include that on your web to lead form, the client can still successfully submit the form with the field blank.

This seems such an obvious problem, and one which causes many unnecessary emails to get the necessary info, that I feel I may be missing something here, so apologies if that's the case! If not, will this be implemented soon?

Many thanks in advance for your feedback on this.

All the best,
Dave