What E-mail service for confirmation of purchase would you recommend?

Question

API

Hello. I am doing my first e-commerce project. You need to make a purchase confirmation by mail to the client. What is the name of such service/service?
How it's done? As far as I noticed from personal experience as a buyer - are there third-party services for this? Like Mailchimp? What are the most common and popular ones? The audience is abroad, it does not runet. Required - free version, preferably - the simplest integration. The more options you offer, the better, I'll try everything))
Or maybe it's not difficult to do it yourself? If it’s not very difficult, then in which direction should I look, given that my entire backend is in JS? Those. PHP doesn't work for me. The site is not on CMS, various miracle plugins do not suit me either.
And about the integration of this service - how is it done technically? As far as I understand, a payment signal must be received from my payment system in order for the e-mail sending to work? Is the work with the service based on the API? Thank you.

Answer 1

From what century?
Hosting with php. You write a simple handler in just a few lines of code!
You send to the soap specified by the user. In general, for ecommerc and a bunch of bare js + html, this is complete nonsense