I administer a few moderate traffic mailing lists. I'm starting to get reports from list members about spam being sent to them after they post to a list. I've been sent a couple of these spam messages with full headers. Looking at these headers, I found that the spammer was pulling the From:, Subject:, Thread-Topic:, and Thread-Index: headers from the list message, then used that info to send spam directly to the poster. (Please note, the spam does not flow through our list server; it's sent directly to the poster's address.)
Because the Thread-Topic: and Thread-Index: values were included in the spam, I suspect that the spammer is getting access to the mail directly and not scraping the web archives or RSS feeds (since those headers aren't available in the archive or RSS feeds).
- Is there anything we can do to stop this spam? We're using Mailman. Converting these lists to anonymous lists isn't an option. We have list posting tied to list membership, but anyone can subscribe to the lists, as long as the subscribe confirms their email address.
- If we're unable to stop the spam outright, any suggestions about how to find which subscriber's feed is being used to feed the spammer? It's not a great option, but at least we can temporarily stop the spammer's source.