[Mailman-Users] Target individual list member with sub-addressing when sending?

Charles Rosenberg chuck at blazingfun.com
Thu Apr 30 02:43:37 CEST 2009

Thank you to everyone who replied and gave me ideas and directions to pursue further.  After reading all of the replies so far, I feel that I should clarify and respond to some of the questions raised to help me and others:

> Brad Knowles wrote: 
> If you want a two-way anonymizing system, that is something you would 
> have to implement outside of Mailman.  

> I'd suggest that you go find some of those two-way anonymizing systems 
> and you talk to them about how you might be able to set them up alongside 
> a mailing list system, and how they could potentially be used in 
> conjunction with the mailing list system.

Thank you for this suggestion, Brad.  I did take a look around to see what was out there.  To be honest, the ones I saw seemed to be a bit overkill for what I need.  After thinking about the setup a lot more, I determined that contrary to my original post, it is OK if the "designated poster" sees and knows the list member's e-mail addresses when they use the "reply-to" mail address.  What can NOT be known by the list members is the "designated poster's" direct e-mail address.  I will look some more on this topic, thank you.

> > 5.     In addition to number 4, I setup a special "reply-to" address
> > where all replies should go to.
> Is the "reply-to" address set to the mailing list or a different
> address?  (I'm guessing different but I figured I had better ask to be
> sure.)

I'm sorry that I wasn't clear in the beginning.  There is only ONE, maybe two(besides me the admin) "designated poster(s)" to the mailing list.  The "reply-to" address is completely different from the list address.  It is one specifically created for replies to this specific mailing list.  It is not used anywhere else.

> > 8.     The "reply-to" address is set to forward the e-mails to the
> > original list "poster" inside of Postfix.
> Are you saying that Postfix has been configured such that the email
> address that replies are directed to (via "Reply-To:" or "From:") is
> forwarded / redirected in to the address used submit new posts to the
> list or somehow magically directing to the email address of the person
> that posted.  (Again I want to be sure that there is no collision with
> the "post" address.)

Again, sorry that this wasn't clear.  Since there is only one, maybe two(besides me the admin) "designated posters," Postfix redirects all replies to the "reply-to" address to a specific e-mail address, namely that of the "designated poster."  The "designated poster" is our school's Host Family coordinator and she will be the only one who will be posting to the list.  Since Postfix knows her direct address, all mail directed at the "reply-to" address will be forwarded to her. (I will probably set it up to send me or someone else in the school's administration a copy as well just so we see what is going out and in.)

> > After receiving a message through the "reply-to" address, I want the
> > original poster to be able to send a single message back to the
> > "replier," possibly answering some question.
> Ok, is this a correct understanding of the sequence of events?
>   1)  Original poster sends an original message to the mailing list.
>   2)  Mailing list sends the original message to all subscribers with a
> custom Reply-To: / From: address.
>   3)  Responder replies to the original message to the mailing list via
> the custom Reply-To: / From: address.
>   4)  Mailing list sends the reply message to all subscribers with a
> (different?) custom Reply-To: / From: address.
>   5)  Responder replies to the reply message to the original poster via
> the (different) custom Reply-To: / From: address.

Close.  Like I mentioned above, since I wasn't clear in the original post(my fault), I hope the above explanation clears it up.  Just to summarize like you have done:

1.  Original poster("designated poster" - our Host Family Coordinator) posts a message to the mailing list.
2.  Mailman sends the message out to the mailing list.
3.  Postfix rewrites the outgoing mails' headers so that it looks like it comes from a custom, specific "reply-to" address.
4.  List member replies to the original post via the "reply-to" address.
5.  Postfix takes the reply to the "reply-to" address and forwards it to the Original Poster("designated poster"), not the entire list.
6.  Problem arises at this point.  Now our "designated poster" wishes to send a reply to the reply, not the whole list.  

> > Problem: I can't have
> > the "poster" know the individual address of the "replier," nor can I
> > have the "replier" know the direct address of the "poster."
> Ok.

I said in my original post that this was the problem, but I was partially wrong(again, my fault).  I can't have any list members know the "designated poster's" address, but the "designated poster" CAN see and know the address of an individual list member without any really problems.  The "designated poster" can't use this information to contact the list member directly however since if the "designated poster" simply uses her cell phone's "reply" function, the recipient will now know the "designated poster's" direct e-mail address.  

> Would it be ok for subscribers to know other subscribers addresses /if/
> the addresses were ""forwarders for the mailing list?  I.e. when ever
> someone sent a message through the list their From: address would be
> translated to their special ""list address?  Similarly any messages sent
> to these ""list addresses would then be forwarded on to the real
> address.  All the while people not knowing each others ""real addresses,
> just the ""list addresses.

To be honest, I think what you are talking about here is one potential solution that I was originally thinking about.  What I was thinking about was creating the list as an "umbrella" list and creating mailing lists for each specific recipient I want.  This would mean that if I wanted to make it as seamless as possible, I would have to have Postfix do some work too.  To summarize:

1.  Create the "main" list, austrailia at lists.domain.com as an umbrella list.
2.  Create an individual mailing list address for each member we want to get e-mail.  i.e. KenYamaguchi at lists.domain.com, JoeTanaka at lists.domain.com, etc. and have each individual mailing list have only one subscriber, namely the person we want getting our e-mails.
3.  Subscribe each of the "individual" mailing lists to the umbrella list.
4.  Continue to rewrite the mail headers to show the "designated posters" messages as coming from the "reply-to" address.
5.  Configure Postfix to rewrite the from headers on the replies to the "reply-to" address so the "designated poster" automatically sees the associated "individual" mailing list for that list member.  i.e. Postfix will rewrite kyamaguchi at docomo.ne.jp --> KenYamaguchi at lists.domain.com when kyamaguchi at docomo.ne.jp replies to the "reply-to" address.
6.  Once the "designated poster" gets the reply, she only has to hit her "reply" button to reply to the reply which should go to the "individual" mailing list.(e.g. KenYamaguchi at lists.domain.com)
7.  Configure Postfix to then rewrite our "reply-to-the-reply" header to strip out our "designated poster's" address and replace it with the "reply-to" address we want all replies to go to. i.e. [From: designatedpostersaddress at softbank.ne.jp] --> [From: reply-to-address at domain.com]

First question about this is that it seems like it would work.  Would it?

Second question, is there an easier way?  This way I have to manually "fix" and configure addresses in Mailman and Postfix and while I don't anticipate more than about 20 or 30 list members at most, it does mean I have to do it all by hand.  
Good side is that the list will only be active for a week or so.  After that, all data gets wiped.

> > Would it
> > be possible to use some sort of sub-addressing, extended addressing,
> > plus addressing, etc. to send a message to an individual subscriber
> > based on a "subscriber" username or something?  For example sending
> > to Australia+KenYamaguchi at lists.seishinonline.jp would cause the
> > e-mail to only go to the subscriber associated with "KenYamaguchi"
> > and NOT the whole list.  This way, neither side knows the other's
> > "direct mail address." Is this possible?  Thanks in advance.
> I think the conditional mass forwarding you are asking for is beyond the
> scope of Mailman.  However, that being said, I think it would be
> possible to set up something to help decide where to send messages and
> conditionally send messages to the mailing list or individual recipients.

I guess since you are not the only one to mention that this would be very difficult in Mailman as-is, I should think about my idea I just posted above this paragraph using the individual lists idea.  As for your conditionally sending messages to the list or individual members, how powerful is Mailman in setting up something like that?  Just for future reference.

Thanks again.


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