[Mailman-Users] Which user is harvesting sender emails?

[Bill Cole]

On 19 Aug 2016, at 10:39, Jim Popovitch wrote:

> PRVS/BATV

How is that relevant to this issue?

BATV only applies to the envelope sender address, which any proper 
mailing list (including any Mailman list) completely replaces with its 
own bounce address so that bounces go to the mailing list software and 
not to the original sender or the list itself. As the OP said, this is 
someone or something spamming the original message authors (as shown in 
 From headers) with the same Subject header as something they've posted 
to a list.