On 21.09.18 19:50, Andreas Krey wrote:
Create a dummy mail address. Make the list server send out mails from that address very slowly at random times to the recipients.
Ah, now you're changing the whole situation. We were talking about using existing ("real") subscribers, and relying on them passing information to the list admins. You wrote yourself: "Unfortunately that requires that every spam addressee to respond quickly".
If you're changing the game, then let me put on my (purely fictional) spammer hat to see where that gets us. :-) Let's imagine I'll subscribe not only a single trigger account A, but a set A1-An. I only react to list posts once a random subset of m <= n accounts (with m varying over time) has received any particular message. Messages can be uniquely identified after all. Also, I can add random delays before spamming, and/or spam after collecting a randomly varying number of addresses before sending out a batch of spam.
That's just what immediately comes to my mind, I'm sure there are more effective methods of erasing one's tracks. The long and short of it is, in my opinion, that all spam recipients need to implement their own spam detection/prevention, and that the mailing list admins would have a very hard time trying to identify spammers when the originating address is not a list subscriber.
-Ralph