SMTP object question

[oyJouokong]

I would like to ask, CheckSMTP method returns SMTP object, HostExists represents whether there is this mailbox, and Deliverable represents whether mail can be sent, then how do I judge, a specified mail, whether it can be sent successfully? Because I found several test mailboxes, some of which failed to send, but checked out, HostExists is true, ask if you need to configure anything?
example email:
[email protected]
[email protected]

[NexaVerse-AI]

FYI - most host will block ports for emails - try find some with good reputation who allows. Also if you can find some please let me know as well. Since we have same problem with ports on major providers.