[Mailman-Users] Client wants unique archiving method

Dragon dragon at crimson-dragon.com
Wed Aug 23 22:02:07 CEST 2006

Andrew Jones sent the message below at 11:23 8/23/2006:
>I just moved a client to Dreamhost from another provider where they
>also had a Mailman discussion list.
>Everything is working at Dreamhost, but they have a strange request.
>They want all original posts to go to all subscribers as normal. BUT,
>they want all replies to ONLY go to the original poster. But they
>also want those replies to be archived so the entire list can choose
>to view them or not.
>I've looked through all of the Mailman config options and cannot find
>a way to achieve what they want, even though they swear this is the
>way it worked with their old host.
>Is this possible, or are they on crack?
---------------- End original message. ---------------------

They are on crack. And you really don't want to get into this can of 
worms. I'm not saying it couldn't be done, but it is not something 
that would be easy nor reliable. See below for the full explanation.

In the standard mailman distribution, you can set up a list so that 
replies go to the list (called "Reply-To munging" and 
despised/deprecated by some) or to the poster. If you set it up in 
the latter fashion, the e-mail in reply will never hit the mailman 
server and you have no way of archiving it. If you set it up for 
reply to list, everything will go to the list and get archived.

The only possible way to even come close to what they want is to 
modify the mailman code. It would be difficult to do and would be 
fraught with potential problems. Each incoming e-mail would have to 
be examined for a number of things to determine if it was a reply or 
not and who it should go to. This means that the In-Reply-To: header 
must be examined to see if there is a matching message ID in the 
archive. Depending on list size and traffic, the archive size and the 
server's processing load, that could be a long and slow process.

If you found a matching message, you would then have to determine who 
the reply should go to. That task is non-trivial and you would have 
to make a number of assumptions that may or may not be valid. If 
there is only one matching e-mail, you could extract the From: header 
from the original post, but if you have the list configured to hide 
the identity of list members (you have anonymous_list set to Yes), 
you cannot do that.

But what do you do if you have multiple messages in a long thread? Do 
you just send the reply to the most immediate poster or to everyone 
in the chain? Is your assumption on what to do always appropriate, I 
would say that it probably won't be.

What happens if somebody replies to a thread by creating a new post 
that does not have the In-Reply-To: header? What about when somebody 
goes off on a tangent and uses Reply-To in their MUA to post a new 
message to the list? (People do these sorts of thing sometimes, there 
is no way you can reliably account for them).

So you can see why I say they are on crack. Tell them to step back 
and take a deep breath of reality.


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