In what sense are protist primitive & in what sense are they advanced? You can only upload files of type PNG, JPG or JPEG. 2  You can only upload files of type 3GP, 3GPP, MP4, MOV, AVI, MPG, MPEG or RM. 3  You can only upload photos smaller than 5 MB. 4  You can only upload videos smaller than 600 MB. 5  You can only upload a photo (png, jpg, jpeg) or video (3gp, 3gpp, mp4, mov, avi, mpg, mpeg, rm).
In answer to your question, you can use a Forever stamp, but it won't be enough on its own. The cost of a US Forever stamp is 49 cents, while the cost of a letter to Canada is $1.20. USPS also sells a Global Forever stamp, as others have noted. You can certainly slap one of those on a letter to Canada.
Canada Post is raising the price of a stamp to 85 cents, up from 63 cents. While the new price applies when buying stamps in bulk, it will cost $1 to buy a single first-class stamp. Large-volume mailers, however, will pay only 69 or 70 cents per stamp.