Long shot, but I'll ask. For a while Thunderbird spam filter will work fine. Then, spontaneously, it stops working and starts showing me many which are obvious, identical junk. And after flagging them as junk, it doesn't seem to learn anything.
For when this happens, it would be nice to have an explicit (and easy) way to blacklist items. Creating new filters for each of them is too involved.
I hope you have spam filtering happening somewhere upstream of your local computer. Spammers are constantly adjusting to find ways around filters, and there is no way a third class open source legacy email client I going to be able to give their filter the continuous attention it needs to stay effective.
Yes. But this is not clever stuff. I'd expect the most simple-minded Bayesian filter to identify it.