> I manage four lists for some 500 subscribers.
> I have recently been getting querires from the subscribers asking why they
> are receiving error posts.
>
> The posts are Rejected posts originating from other subscribers.
>
> I have no idea how they are getting them.
 
Some email systems send bounce messages to the From address of the message,
rather than the SMTP MAIL FROM (envelope from) address, which is the place
that Internet Mail standards call for error messages to be sent.