Lettermail is within Canada. Has a 2 cm thickness limit. Weight up to 500 grams. No delivery confirmation so expect some items to be falsely claimed by buyer as Item Not Received.
Lettermail can contain paper or goods within Canada. You can use regular envelopes, padded envelopes, even small boxes. As long as they are under dimensions and weight maximums.
Letter post is the name for letters outside Canada. USA, rest of world. Same rules for dimensions and weight. However it is supposed to be non commercial goods and paper like documents. Never enforced much but world mail systems may enforce much more today.
Many sellers disregard the rules for non commercial goods. Use at your own risk.
When mailing items avoid the post office counter because they will check packages for Lettermail and Letterpost. They have a thickness template to check 2 cm thickness. They will ask what is inside package.
Have postage stamps at home to make the various rates and a tape measure and weight scale. Drop in the nearest corner box or box in front of post office.
You can buy “discount Canada postage stamps” on eBay at about 60-80% off face value and often no sales tax. So you save roughly 50% off the cost of lettermail in Canada
Others will post more information.
