Yes, you can mail international letters from your home as long as you weigh them and look up the postage price and put the correct amount of stamps on them. 
The USPS has a postage calculator here:
https://postcalc.usps.com/
Also if you are putting any extras inside you envies, then your letter has to be less than 1/4 inch thick too.
https://pe.usps.com/text/dmm100/mailing-domestic.htm
I got lovely cheery happy mail from @Amfkinney
you made my day
This is the USPS model, but if you have a box for mail delivery (most single-family addresses) then you can also send letter-sized things out from there, or usually schedule pick-ups of packages online.
So the posties pick up mail from your mailbox and push it down the chain? That sounds amazing!
ok, thanks so much!
also thanks to @AIMR for replying == I have read about using online postage for pkgs (although I haven’t pulled the trigger on using it yet 
) but wasn’t sure about regular cards/ letters going internat. Good info, thx!
Now I need to check the info about postage to Canada – I remember reading about it, but my brain doesn’t retain stuff like it used to~
@Renstar, our postal collection boxes aren’t nearly as cute as those! (as you can see from the photo above)
Yes, you an drop it off at a center, in the boxes , like above, or have them pick it up…in fact, if your flag is up and they don’t pick it up, they can get in trouble! They also have to use sidewalks to delivery packages to your front door unless you give permission to cut through your lawn.
lol my postman is getting a kick out of the mail I am getting…he yelled out of his truck today that I got a postcard from Germany…
Thanks, @Ewulotta …omg, your handwriting is so perfect that at first I thought it was an advert piece! lol
I totally forgot about the postcard 
Is it the one with the Schwarzwälder Kirschtorte?
that is so cute about the mail carrier enjoying your happy mail along with you!
and I had not heard that about them not being able to cut through yards without permission~
and on a side note, (related to the discussion about postal collection boxes)
when we traveled to Brazil several years ago, my dtr wanted to mail some postcards, and we had a devil of a time trying to find any sort of postal box! Finally at the airport as we were checking in for our flight home, she asked the clerk at the counter & they had to ask 2 other clerks before one knew where to find a place even in the airport that she could mail them…
I guess I had always taken for granted that every country’s mail system would be similar, with postal boxes easily accessible, but it wasn’t for us at least that time.
For international mail (envelopes) I stick a “global forever” stamp on them. If they are rigid or slightly fragile I’ll add a “non machinable” stamp and/or if they weigh extra I’ll add an “extra ounce” stamp. I’m sure I often over stamp letters but it’s easy and I’d rather pay too much than have it come back to me. And I usually drop them in the residential mailbox thingy at the end out our street where I pick up my mail.
@Renstar I think it’s becoming more common (at least in cities) to have these:
Multiple addresses in one spot. Every address has a locked section and there is a slot for outgoing letters too. The bigger boxes at the bottom are for packages. The mail person will put the package in there and the key to the box in the right mail box slot. If I’m over explaining or you already know about these then please forgive me! That picture is similar to the one I use.
Yes - this is what I have as well. I also think I may over-postage my letters for the same reason!
Still reading thread, so probably answered already, but yes!
We have this style in our neighborhood too, except ours doesn’t have the larger package ones at the bottom.
We had that in most of our office buildings and also most condo or apt complexes…it is way more efficient than going door to door…
In our area, our mailboxes are grouped 4-10 at the end of a street or block. The mail truck stops and fills those then drives down the street to next group…it was a great place to gossip with the neighbors before COVID…in my old neighborhood, the mailman walked with a mail cart and walked up to the house…he sure got his exercise daily!
Sadly our mail person ignores our flag when I put it up. I’ve learned to just take them to the post office or find a mailbox to pop them in.
I send in a complaint and get called to make sure it is fixed. They take service here seriously!
I received a beautiful, fun, wonderful June card from @Ewulotta 
Thank you!
I also bought a letter opener today 
I feel so grown up and retro 
I think I’m just glad they don’t throw our boxes at our door like at the last place we lived. I did complain about that multiple times. Heh.
I got some crafting in for happy mail. Very satisfying. I’m going to have to create a spreadsheet of who I am sending to and what I’m sending. Because I complicate things when I get excited and inspired. I realize that none of this probably makes sense but it will. Heh.
