[Mailman-Users] How many is too many?

[The Berean]

Hello all,

I'm doing some research in an attempt to find the
ceiling on how many users I can have on a Mailman
powered listserv.  I understand the record so far is
147,000 users, but that listserv in question is an
announce-only list.  The listserv I have in mind is an
interactive listserv (listserv as a forum).  For those
who run large listserv forums, how many would you
figure could join such a list before the conversations
starts becoming chaotic and the mails become far too
excessive?  What could I expect in terms of bandwidth
from a listserv forum of 20,000 people for example? 
If you can point me to resources where I can do
further research Id appreciate that as well.

I need to determine what limit I should set before
closing the list to new subscriptions, and costs,
affordability, especially on the bandwidth a large
listserv forum will undoubtedly generate.

Appreciate any help!  Happy Holidays,

Berean

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