This list server is better than any other I have used.
It requires confirmation of email address, which is common.
But it also does not accept email from non-registered email addresses.
I have never seen this feature before.
When spammers use lists to spam, they don't send from a registered email
address. They tend to use fake email addresses. However they may register
just to harvest email addresses. The list server can't stop this.
I have never been spammed by this list server, yet!
Theoretically a spammer could register to send spam, even it has not happened
on this list as you claim.
I am glad spammers are not doing that!
Thanks,
Shelby