So I don't think they have sent out emails yet but I saw a banner on the news tab declaring poshmark moving back to CP as a shipping provider with the previous $13.49 flat fee shipping rate.

It's going into effect tomorrow which is pretty fast. They also link an FAQ

Why are we switching back to Canada Post as the only shipping provider on Poshmark?

We have been working closely with Canada Post over the past week to create the best solution that will help streamline our shipping system for all buyers and sellers across the country.

I recently made a purchase using Purolator. What happens to my order?

Rest assured that all confirmed orders placed using Purolator will remain active. This change only applies to new orders placed after 12 AM PT on June 30, 2022.

What happens to current offers that are accepted after this change goes into effect?

Any current offers accepted after 12 AM PT on June 30, 2022 will receive a Canada Post shipping label for the completed order. The cost for the new Canada Post label (C$13.49) will be reflected in the shipping price. Your package will be sent to your listed default shipping address. If you need to update your home delivery address, please contact us at [email protected].

I recently sold an item with Purolator and have scheduled a package pick up at my house. Will Purolator still come?

Yes, all confirmed orders placed using Purolator will remain active and your previously scheduled pickup with Purolator will still happen.

Can I still schedule a Purolator package pickup?

Yes, if you have an active order with a Purolator shipping label, you can still schedule a free package pick up or drop off your package at your closest Purolator drop off location.

Can I now use a PO Box address to ship from / ship to?

Yes, Canada Post accepts PO Box addresses for returns, as well as for deliveries.

I still haven’t received a label for my order. What should I do?

Please reach out to [email protected] so the team can help you out. Note that our current response time is longer than usual right now due to an increase in volume. We appreciate your patience as we work through your inquiries.

What is happening with seller shipping discounts?

As a seller, the total shipping discount you choose to offer will remain the same. Shipping discounts will continue to be based off of the C$13.49 shipping fee for your buyer. If, for example, you offer a C$3.50 seller shipping discount, your buyer will get C$9.99 shipping on that item (C$13.50 – $3.50 = $9.99).

Will Purolator still be an available shipping carrier?

No, Purolator will no longer be an available shipping carrier on Poshmark effective 12 AM PT on June 30, 2022.