Tom,
thanks for doing the research, so we have some indication that Precedence: bulk can
indicate other email systems to not send an automated reply. But also rfc2076 (an 
informational rfc) that it is "discouraged".  So my next question is: Which software
actually will filter out Precedence:bulk?

I think that roundup's message do not qualify as "bulk" in the sense that a lot of them are 
send right way. Usually nosy lists are quite short I presume.

We have a number of mailman mailinglist and I think roundup nosy messages go right through 
to them, even with the roundup devel mailinglist, I think this is also mailman. 

Tom, are you positive that Mailman is dropping it by default? Or is there something special
about your mailman installation? Which version of mailman anyway

I think the we could drop the header or make it an option, it does not seem to be necessary 
today.