We've added patterns to verify whether an answer meets the requirements. You can use them to check whether e.g. an email address has an @ and a TLD (.com, .nl, etc.). As long as these requirements aren't met, the question will remain unanswered.
You can enable this whilst adding a question in the tab Advanced (see below). For now you can only select email address or postal code. If you want your own pattern, please let us know!