It's the further processing after that which I'm interested in. Sanitising the input should probably be rejecting/replacing with a space any non-printable code

It's the further processing after that which I'm interested in. Sanitising the input should probably be rejecting/replacing with a space any non-printable code points or weird whitespace characters. But what about sending emails? "Dear <name>"? There are probably other situations where this is a problem.