[Mailman-Users] Dealing with spam

[Henry Hartley]

I have a few small, private lists managed with Mailman. For the most 
part, I don't have problems with spam, probably aided by the fact that 
they are both small and private. Lately, however, on one list (about two 
dozen addresses) I'm getting spam that has valid users as the From: 
address. My first thought was that the users' machines were being used 
as spam bots but at least one uses my server as it's mail server and 
these messages are coming from other servers. So, it seems that their 
address is being spoofed and being used to sent mail to the list (even 
though it isn't advertised).

For the most part, messages are coming with implicit destination so I 
can simply discard them but occasionally they come directly to the list 
and are not filtered. I have two questions:

1) What is the best practice approach to dealing with these messages? I 
have simply been discarding them. If I reject them, will that send a 
response back that might make an automated sender drop my list address 
from their list as a non-working address? Or is that wishful thinking?

2) Is there some way to automatically reject or discard mail with 
implicit destination rather than holding it for moderation? The users of 
this particular list do not (ever) intentionally use an implicit 
destination so I wouldn't mind just automating that. There doesn't seem 
to be a setting on the Recipient Filters page of Privacy options.

Thanks.

-- 
Henry