Canada Post is on strike. I don't know the details of how the rotating strike is working day-by-day, but my impression is that the entire country is pretty much without mail service right now: no pick-up, no delivery. I've heard that postal workers in the USA aren't even accepting packages for mail to Canada right now. (My thanks to 100 days of snail mail for the most recent update.)
I gather there is legislation brewing to address the striking postal workers - I don't know the politics of the situation, but given my sympathy with postal workers, I really don't want to be quick to place blame on anyone - and I sincerely hope our Canadian friends will get their full mail service restored soon!
