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

Charles Rosenberg chuck at blazingfun.com
Fri May 1 03:00:11 CEST 2009

Thanks again for the reply.  They have given me some ideas to think about to 
make it all more streamlined.  Please forgive me again for not making 
something clear enough in my previous reply.

Grant wrote:
>> 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.
> I don't think you will want to create a separate list for each subscriber, 
> that would be way over kill.

The reason for giving each member a separate, individual mailing list is 
precisely how I was thinking of sending a mail to the "subscriber" 
"directly" all the while sanitzing the "designated poster's" address.  I 
explain more below.

>> 3.  Subscribe each of the "individual" mailing lists to the umbrella 
>> list.
> Yes.
>> 4.  Continue to rewrite the mail headers to show the "designated posters" 
>> messages as coming from the "reply-to" address.

I am already rewriting mail headers in Postfix so that ALL mail going out to 
the mail list, (austrailia at lists.domain.com) through Postfix(AFTER it has 
been processed by Mailman) shows as coming from 
reply-to-austrailia at domain.com As I mentioned before, using ONLY the 
built-in Mailman support for redirecting all replies to a specific address 
doesn't work for me because most of the people involved will be getting the 
messages on their cell phone.  The cell phones here don't seem to understand 
the "Reply-to: " part of e-mail headers.  Thus, I have to completely rewrite 
the headers. (Not smartphones.  Japan has had cell-phone e-mail in common 
use for about 8-10 years now.  Ask anyone in Japan for their e-mail address 
and they won't give you a computer-based one, but the one for their cell 

>> 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.
> I'm thinking that Mailman may be able to do what you are wanting to do 
> after all.  That is /IF/ we are very careful with what we do.

I'm sorry that I wasn't clear with this step.  What this step implies is 
that Postfix ALSO knows which subscriber is associated with which individual 
list.  Postfix will check any mail coming in to the "reply-to" address and 
then rewrite the incoming message headers with the associated individual 
mailing list for that subscriber.
Mr. Ken Yamaguchi is a subscriber and he replies to the "reply-to" address. 
His cell-phone e-mail address will show up in the message's From portion 
when it hits the Postfix mail server.  Before delivering the message on to 
the "designated poster" via the "reply-to" address, Postfix rewrites Mr. Ken 
Yamaguchi's message's From header to be that of the individual Mailman list 
address that was created specifically for him.  Now, the message is ready to 
be sent off to the "designated poster" with the "updated/new" From address 
which is the Mailman list associated with just him- 
KenYamaguchi at lists.domain.com

>> 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)
> Ok...
> Can the "designated poser" reply (from his/her ""public address) directly 
> to the recipient that replied to the original post?

Yes, because of step 7 below, which is where I wasn't clear enough before 
and I apologize for.

>> 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]
> Ok.

Here is where Postfix has to pull its weight again.  Now, after 5 above, our 
"designated poster" has a message from Mr. Ken Yamaguchi, but with a From: 
address that goes to his individual Mailman list, NOT his direct e-mail 
address.  When our designated poster hits "REPLY" and sends a message, of 
course the message will initially contain our "designated poster's" real 
e-mail address.  That is ok because once the message gets to Postfix, before 
passing the message on to Mailman, Postfix will rewrite the From: headers on 
THIS e-mail too to change it from the "designated poster's" email address to 
that of the "reply-to" address.  Once the From is rewritten with the 
"updated/new" address(the "reply-to" address) Postfix hands the now 
sanitized message off to Mailman which will do what is necessary to get the 
message to Mr. Ken Yamaguchi.  The "individual" mailing list address is key 
to this.  It forces the returning messages from the "designated poster" to 
go through the server where it can be sanitized.

After thinking about this, since the "designated poster's" address gets 
sanitized in the beginning anyways, setting up the Postfix rewrite rule in 
step 4 carefully would also sanitize the "designated poster's" address at 
this step too without too much work.  Either way I guess.  Anways...

> Now let me lay out what's in my head:
>  - Create a "reply" list.

I like the idea of a "reply" list.  I might see if that would work better 
than just an address.

>  5) The "reply" list will send the message on to all designated posters 
> unmodified.  This will allow the designated posters to see the real email 
> address of the subscriber which they can reply to.

See above about this.  Actually, what I was thinking was that Postfix WOULD 
modify the messages.

>  6) This is where my I'm stuck.  How to have replies from the designated 
> poster be sanitized and sent back to the subscriber that is replying.  I 
> wonder if a two way anonymizer would help here.

I hope that my explanation above is much clearer this time.  Sorry about the 
confusion.  You are right.  This is the point that causes the problems. 
That is why I was thinking of having ALL messages go through the 
Mailman/Postfix server by using "individual" mailing list addresses for EACH 
subscriber.  If I can make ALL messages go through the server, then I can 
rewrite what I need to to make sure the subscribers don't know the 
"designated posters'" addresses.  As a side benefit, not necessary at all, 
this way the "designated posters" also won't see the subscribers' direct 
e-mail addresses.

What do people think?  To me this seems like it will work, but I can't be 
sure until I try it out.

> I will do some more thinking about ways to allow the original posters to 
> reply to replies that come in to the "reply" list from subscribers while 
> hiding the original posters address.

Thank you very much for taking the time to think and help me out about this. 
Even just having someone to bounce the ideas off of is a big help for me 
getting this all worked out.  I appreciate it.


More information about the Mailman-Users mailing list