[Mailman-Users] disappearing CC lines

Mark Sapiro msapiro at value.net
Fri May 19 07:02:27 CEST 2006

Patrick Bogen wrote:

>On 5/18/06, Imre Gergely <imre.gergely at astral.ro> wrote:
>> i have some problems with a mailman list.
>> if i send from user A, to list L, and CC to B and C (where A,B,C are list
>> members on the same list), the mail i got back from the list (to user A) is
>> missing a CC address.
>> i mean when i look at the message (using firefox) there is only one user (B) in
>> the CC list, the other one is gone.
>Is user C a member of list L? Mailman tries to not send duplicates,
>and it may in fact do this by stripping the address from the CC and
>sending it as a normal list post.

Patrick is correct as to what happens, but it is a mystery to me why
this is done. The AvoidDups handler makes a list of all explicit
recipients of a message (addresses in To:, Cc:, Resent-To: and
Resent-Cc:). It then goes through the message recipients (normally,
the non-digest list members with delivery enabled) and any message
recipient that is a list member and has DontReceiveDuplicates set is
removed from the message recipients so that address doesn't receive a
list message because it presumably receive a directly addressed
message. So far, so good.

But then, for reasons I don't understand, AvoidDups then removes this
address from the Cc: header, if that's where it was. It doesn't remove
it if it is in To:, Resent-To: or Resent-Cc:. It just removes it from
Cc:. It is not clear (to me at least) why.

But the bottom line is any address in Cc: that would otherwise have
received the post from the list and that has DontReceiveDuplicates set
will not receive the post from the list (because it presumably
received the Cc:) and will be removed from the Cc: header of the
message sent from the list.

Note that this does not affect digest members who are in Cc: because
they will not be candidate recipients of the message.

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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