How to check the sending status of an email?

Question

SMTP

Who knows how to check the sending status (for a non-existent email)
For example: [email protected]

phpMailer SMTP is used for sending

Answer 1

No way. There is no such thing as "confirmation" for SMTP.
On the contrary, many admins set up servers in such a way that when they receive a letter to a non-existent user, they do NOT answer ANYTHING and do not give potential spammers extra information.
You can try to focus on error 550, but again, it may not be returned.
Some mail clients have a "confirm receipt and read" checkbox.
This is a feature of the mail client, it is not supported in the SMTP protocol.
If the mail server on that side or the mail client on that side support it, they really just send the status email back. (In a corporate exchange, this may be at the protocol level, but this is not necessarily supported even between two exchanges, since usually the transport between two separate servers can be SMTP)

Answer 2

If the email does not exist, the sender will receive an appropriate email. The letter can be of different content, for example:

Delivery Status Notification (Failure)
Mail Delivery Subsystem
Address not found
Your message wasn't delivered to [email protected] because the address couldn't be found, or is unable to receive mail.
The response from the remote server was:
550 #5.1.0 Address rejected.

Answer 3

No way.
I can, when receiving on a non-existent mailbox, redirect it to an existing one - so as not to arrange "communication of robots by mail" when MAILER-DAEMONs begin to actively communicate on the topic of which of them does not have a user. And at the same time so that it is not clear whether there is a box or not.
When receiving on an existing mailbox, I can return the answer that the mailbox does not exist - for example, if I consider the sender to be an eccentric ...