You can no longer start or prepare a 2018 return on-line (nor can you e-file a 2018 return). If you have the 2018 Desktop software (for installation on your PC you may still start, prepare, and file a 2018 return but you will have to mail it to the IRS.
When mailing a printed return it is always a good idea to go to the Post Office and mail it 'Certified' with 'Return Receipt'. That way you will have proof that they received it and when it was received.
