How to send emails from the site for free/cheap?

Question

Mail server

How to send emails from the site with various notifications for free/cheap?
I saw a bunch of similar topics, but in the answers everyone writes that no one sends through their mail server, you won’t send much through gmail or Yandex servers either, but how forums work, for example, there are subscriptions to new notifications about answers in the topic, etc. n, as a result, a fairly large number of letters per day is obtained.
Through paid services it is too expensive, 0.1-0.2 rubles per letter.

Answer 1

no one sends through their mail server

some kind of nonsense
Any hosting has a mail service ... you just have to send an email using the mail function

Answer 2

there are services with free limits (yes, the same Amazon)
and inexpensive ones
and you can do it from your own server,
but in everything there are nuances,
most of all with your own server, that’s why they don’t send
100-200, they fit perfectly into the Gmail API / SMTP
and Yandex too near