I don't have any specific knowledge about that, but I would look at what happened in B.C. recently, because they've used mail-in ballots for a few different elections in recent memory, one during the pandemic. They saw a high turnout in their last election—I think it was over 30%—and they didn't have any issues in terms of anything being fraudulent or any other kinds of concerns.
They did focus a lot on clearly conveying the process to get a mail-in ballot, use it and then submit it. They put a lot of energy into making that crystal clear, and then people were able to do it, so we shouldn't underestimate Canadians.