Tom, Richard,

thanks for your remarks!

What I learn from it is:
a) Dropping emails with "Precedence: bulk" does not seem to be a general
problem with mailman, but with a local modification within the
University of Washington. So they could add a customer to strip this
header from emails that have the roundup header set and would be done.
So we probably look for other real world examples where setting
"Precedence: bulk" is a problem.

b) On the other hand, rfc2046 discourages setting "Precedence: bulk",
so it should not at all be necessary. Setting no return-path seems a
regular message, but I don't think we should use it outself. If roundup 
does not react to automatic emails we would be fine to prevent loops.
So here also the question is: In which real world situations would 
roundup emails without this header be a problem?