Can you help which email option you are trying ?

If it is Email passwordprotected PDF radio button on Print dialog, then it uses tax payers email entered in information worksheet as to address.
 
If email address is not entered in the return , error prompts saying "The taxpayer's email address is missing."

So, please check if tax payer's email is entered correctly.

If correct email is entered, then email will be sent to the taxpayer.