TTax DOES NOT mail anything.
You are responsible to press the SUBMIT/TRANSMIT button to e-file your tax return, or you are responsible to PRINT and MAIL your tax return. When you mail your return it is best to go to the Post Office and send it via Certified Mail with a return receipt. That way you will have proof that it was sent and when it was received by the IRS.
If you are referring to your tax refund the IRS (or state) will send that to you --again TTax is not responsible for sending our refund.