[Mailman-Users] duplicates

Marco Stoecker marco at stoecker-family.de
Wed Oct 21 08:15:22 CEST 2015

On 10/21/2015 02:40 AM, Mark Sapiro wrote:
> On 10/20/2015 04:45 PM, Marco Stoecker wrote:
>> I see a pattern now, when duplicates occur and it may have to do with
>> mailman.
>> If someone in a list send an email to two or three lists on the same
>> server, the recipients of the list will get two or three times the same
>> email. If it is sent to one list only, no duplicate occur.
>> Any glue what the root cause could be?
> If you are saying that people who are members of more than one list
> receive a copy from each list of which they are a member when a post is
> sent to multiple lists, that's the way Mailman works.
> I.e. If I am a member of list1, list2 and list3 and someone posts to all
> three lists, I will receive a copy from each list.

No, what I was trying to say is, I have a list member which is also
allowed (via accept_these_nonmembers) to write to other lists but is not
a member of these other lists.
So if x at y.com sent an email to list1 at mydomain.com and to
list2 at mydomain.com and x at y.com is only member of list1 at mydomain.com than
x at y.com gets a duplicate email as well as all members of these two lists.
Furthermore if that email is also sent to list3 at mydomain.com, than the
members as well as x at y.com will receive 3 identical emails (content wise).
It seems to me as if mailman, when it hands over to postfix, duplicates
the email so many times as to so many lists the emails was sent. But
this is only my suggestion. I have no idea, where to look into. The
mailman logs and postfix logs gave me no clear picture.

> The list member setting "Avoid duplicate copies of messages?" (nodupes)
> does not affect this. It only affects whether I receive a list copy if I
> am also a To: or Cc: addressee of the post.

This is already set in the intended manner.

> The list's Non-digest options -> regular_exclude_lists can modify this
> behavior somewhat. E.g., if the regular_exclude_lists setting for
> list1 at example.com includes list2 at example.com and list3 at example.com and
> the regular_exclude_lists setting for list2 at example.com includes
> list3 at example.com, then a member of all three lists will receive a copy
> of a post sent to all three lists from only list3 at example.com.

I do not use the regular_exclude_lists
> regular_exclude_lists need to be set up with care. In particular, if
> list2 at example.com is in list1 at example.com's regular_exclude_lists,
> list1 at example.com MUST not be in list2 at example.com's
> regular_exclude_lists or a post sent to both lists will not be received
> by anyone who is a member of both lists.
> Note that in the above, member means non-digest member. Digest members
> are not affected by this.

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