The hard copy paper versions would also be required for most accounting purposes. I am sure businesses and Revenue Canada require a bit more paper than an email, even in print out fashion, can provide. I have a few faxed e-tickets from the time I had one of those more primative thermal paper fax machines. The ink has faded so much, one can barely make out the details, so I am sure Revenue Canada would appreciate more lasting versions in my files should they come around for an audit.