Shipping flat rate to Canda, can I go to USPS and print a lable using a flat rate envelope ?

Question

I'm trying to get my pkg ready on a Sunday

I already have the appropriate mailer envelope for Canada I just wanted to know if I could print an online USPS to Canada

Answer 1

$11 if it's priority flat mailer, they should let you print it online.

Answer 2

. 'Ready' on Sunday? , 'cause this IS Sunday!
/...or mailed on Monday?
Anyway, my regular Flat Rate envelope which is right in fron of me say, "Domestic Use Only". I'm thinking that means it's Only for the US of A.
BUT the usps site below says: "...the easy-to-use Flat Rate Envelope. Just like the Flat Rate Boxes, this paperboard envelope features a predetermined rate of $4.60 regardless of the weight or destination zone of the package.

Some key benefits:

-Can be used for Domestic Priority Mail ($4.60) and International Priority Mail ($9 to Canada and Mexico- $11 to all other countries, 4 lb weight limit applies) . " ...
.. so IF it's marked for International @ $9, I guess it'll go.
As for shipping labels, that looks easy @ the sss site.