Hi,
The problem is that some of the spam mails are "detected" and other spam mails are not. The ones that get detected will be reported to the moderators. They can still be approved by the moderators if they are "false positives", but the real spam/fishing etcetera does not get approved and gets blocked: forever. Your last message about "all this wire transfer" was also marked as "possible spam" based on the other ones, but passed through "the filter".
You can never prevent spam from a "new sender" to a mail group unless all messages pass through the moderators. The amount of mails is now much lower than a few years ago, but still the moderators don't want to go through every email. I used to be a moderator and still have that "elevated access", but currently I am in the background occasionally doing some moderation.
I personally already blocked 11 spam messages today and 17 from past week, even as "only" a "far in the background" backup right now. I do not know how many are actually blocked.
We also have the option to remove older mails from the mail group itself, but if you receive emails (gmail, webmail, pop3-mail) they are already in your account, and that is already too late to remove them. Users "only" reading in the mail group itself will see them "disappearing", if they had already spotted them anyway.
It is a dirty job, but someone has to do it. ;)
Harry