New York E-file - Is It Free?

I have prepared a New York State return (first time) for one of my children.  Edit message says that New York State return MUST be e-filed.  When I print out the return from TurboTax it does not say this, and it gives a mailing address.  The edit message also said that the e-filing is free, and is part of the software.  I am using the five e-file allotments from TurboTax for very large federal returns.  Is there an exception for NY State?  What happens if I mail the return provided in the Turbo Tax File by Mail Instructions?