Question:
How can e-mail be determined to exist in php? Of course, you can send requests through this curl service . But I would like to know how they did it.
Answer:
Not sure if this is PHP programmed.
Apparently, it is most realistic to try to connect to the server (having learned its address by MX in DNS) via SMTP and "start sending mail", send as a result
RCPT TO: проверяемый@адрес
and if the answer is yes, then we can assume that such an e-mail exists.