Presumably they know what your IP is because they gave it to you. That’s the authorization.
I am willing to bet that if you tried to send mail from off network you wouldn’t be able to without doing SMTP auth Sent from my iPhone > On Jan 12, 2020, at 16:15, Wesley Peng <[email protected]> wrote: > > > Hello > > My ISP email even doesn’t require SMTP AUTH. Will they be acting as open > relay? How to stop abuse of outgoing mail? > > Regards
