What are the services for sending paper letters (direct mail) with API?

Question

API

Good afternoon,
There was a need to send personalized paper letters to customers of the online store at the time of placing an order.
I would like it to look like this:

1. There is a need to send a letter
2. We form the text of the letter on our side
3. We pass the text, the name of the recipient and the address to the mailing service via the API
4. The service prints a letter, packs an envelope, sticks an address label
5. The service sends an email and provides a tracking code via the API
6. The cost of these transactions is debited from our balance sheet.

What are the services that allow you to implement this as painlessly as possible?

Answer 1

For example www.napishi.ru/interface.asp?Lang=ru