PC...Pre Covid 19 Calgary to Vancouver by Expedited was almost always overnight with following day delivery. Now routinely 3 to 6 days
Calgary to Toronto/Montreal by Expedited was 2 to 4 days. Now 8 to 12 days. Add a day or 3 more for outside those cities.
Maritimes was 6 to 8 days. Now 10 to 14 days. Really depends on how rural.
In the past US mail went Calgary to Richmond overnight 8 times out of 10. Richmond to LAX or SF normally 4 days plus a day to process then out from there with scans for expedited Calgary, Richmond, LAX/SF. Lately no consistency what so ever. My most recent shipment went Calgary 13th...Winnipeg 19th, Mississauga 21....So it appears it is Taking the Long Way Home.
Last but not least recent shipment to 2 hours outside of Greater Montreal was quoting 6 to 10 days for Xpresspost(1 day handling). Was in Mtl overnight(Friday) and delivered after the holiday. Customer was thrilled.
If a customer asks, best recommendation I can think of, spin a wheel with a bunch of random numbers and let them know + or - 5 days either way. No guarantees. 
-Lotz
PS. Anything i do happen to mail letter service rarely hear back. Maybe for a timeframe for that service eBay could suggest.....Sooner or Later....No Guarantees!!!
@lotzofuniquegoodies wrote:
If a customer asks, best recommendation I can think of, spin a wheel with a bunch of random numbers and let them know + or - 5 days either way. No guarantees.
-Lotz
PS. Anything i do happen to mail letter service rarely hear back. Maybe for a timeframe for that service eBay could suggest.....Sooner or Later....No Guarantees!!!
Inspired by this idea we should have the Delivery Not Guaranteed tag made available for listings. At this point no service is guaranteeing anything other than delays. eBay's corporate response has been a bit baffling, while other competitors are going out of their way to manage customer expectations and very clearly moving away from a model of delivery certainty we are seeing a odd mix of strategies from ebay: Overpromise to get the orders then pivoting to block this country for no apparent reason.
From a user experience it is a bit of a mess for an ebay shopper at the moment as countries are blocked that shouldn't be, ones that should be aren't, listings are getting erroneously tagged with same day shipping, delivery estimate days aren't reflecting the reality on the ground, and so on. Perhaps during a time of uncertainty there should be less emphasis on buyer certainty. Some of the carriers here are having delays of up to 4 weeks for shipments within a 100km space. First in last out seems to be more frequent now.
The most likely result is:
-The item is not lost.
-Your buyer is not scamming you.
April oversized lettermail was very bad. I have had packages take over 30 days within the same province. I have refunded buyers, and had them message me because their item arrived, and they want to repay me.
The upside is that, as of now, items sent in May don't seem to be as bad, but they are still taking long. It is very touch and go.
How I have chosen to handle this is:
-Buyer contacts me, I politely explain the current realities of the mail system. Instruct them to message me if their item doesn't arrive by the expected delivery date so that I can provide further assistance.
-If it doesn't arrive by the date, heavily emphasize that it is not lost, but if they no longer wish to wait, offer a full refund. Politely ask that they don't open the package, and return it to their post office as refused.
-Assuming they take this refund, I also let them know after refunding them that if they choose ot keep the item, I can also send them a new invoice when it arrives
Obviously, you can get scammed, because people realize oh sweet he has no idea if it arrived, so I don't actually have to mark it as returned to sender or ask for another invoice. But that's the cost of dealing with lettermail, and MOST people I've dealt with are cool.
If someone opens a case before messaging me, I explain that it almost certainly isn't lost, and that I will resolve the case by refunding on X day (the last day I have to refund it). While asking them to close the case if it arrives. After refunding, I message them instructing them to refuse the package or contact me for a new invoice when it arrives.
I've gone as far as to subsidize expedited shipping, while making it blatantly clear that "free" shipping via letter mail might take 30 days. Even at an additional 6.49 a pop for shipping that costs me sometimes as much as 15 total, most people choose the free shipping. It's also possible, that most people (especially on mobile) don't read the listing before buying. Ironically, it's never the people in Ontario where I'll come close to breaking even on Expedited shipping who buy it, it's always the ones in BC or Alberta where it's going to cost 15 
For anything going lettermail, set your shipping to "Economy Shipping". This will give a much more realistic time frame for a worst case scenario. I also think it is important right now to message people when you ship their item. Just draft up a stock message that explains you've dropped it off with Canada Post, and that while you do your best to ship things quickly, in some cases items are taking 20-30 days due to COVID-19. I also usually photograph the actual letter mail package at my post box and attach that so they know I'm not just saying I sent it, but I understand that is overkill. I think when buyers know that I have in fact sent their item, they are more comfortable waiting because they trust I did my job.
Good luck!
