I say this because the My Account service allows a Canadian to check their balance, payments, credits, filing status, etc. It's there for anyone, ready to go, with whatever information the CRA has stocked it with. Your information, even if it started out on paper. It's pretty inconceivable that the CRA could function if the paper filings didn't soon end up in the same database as the e-filings.

Anyways, then at that point, your paper personal data is sitting right there behind the login of that same CRA site we're talking about. For your future convenience. Or leaking. Or hacking. And then we're back to ... "in the event of such occurrences, the Canada Revenue Agency is not responsible for any damages you may experience as a result."