[Mailman-Users] posts repeating in digest for some users

Mark Sapiro mark at msapiro.net
Mon Jun 20 18:51:59 CEST 2011

marci   Boskie's Mama =^..^= wrote:

>    I just received email from a couple of my list members saying 
>that they are getting repeats of some posts in their digest version 
>on the mail .
>  As moderator, I subscribe to both the individual mail and the 
>digest  and I am not seeing repeated posts .
>  I ve requested that  they send me a copy of the digest they are 
>getting so I can see what is happening.. but the two that I have 
>heard from are both on Bellsouth .
>   Is it possible that there is something  with Bellsouth that would 
>cause some posts in a digest issue to repeat for their customers but 
>not for anyone else.. ? ( eg. Post # 3 in a digest would be repeated 
>twice  but only for some users )
>   I was under the impression that the digest sent out would  be 
>identical for everyone.

There are two digest formats, plain text and MIME. The plain digest is
identical for all users it is sent to, and likewise the MIME digest is
identical for all users it is sent to, but the two are different. In
the plain digest, all messages are flattened to plain text and any
non-plain text attachments are stored aside and replaced by links,
while in the MIME digest, each message in its entirety an attachment
to the digest. The rendering of the MIME digest is heavily dependent
upon the MUA (mail client) used to read it.

However, I suspect that there is in fact no Mailman problem. Do the
duplicated messages appear twice in the table of contents? If so, they
were probably actual duplicate posts and are duplicated in everyones
digest. But, my guess as to what's actually happening is that there
are two posts in the digest, one of which quotes the other in its
entirety and thus the content of the first post appears twice in the
digest and appears to be a duplicate, particularly in cases where the
original content in the second post is no more than "me too".

This is a real issue with the plain digest when people quote
excessively. It can be almost impossible to find the original content
amongst all the quotes of quotes of quotes. It gets even worse when
digest members quote the entire digest in their replies. I catch most
of those by having a fairly small max_message_size.

I have not found a good solution to this. If any one has a reliable,
programatic way to determine the ratio of original text to quoted text
in a post, I'd consider implementing a feature to hold posts where the
ratio is too low.

I ask people not to quote excessively, and I have even sent copies of
the plain digest to major offenders. This may work for a post or two,
but they soon return to there old ways. A major contributing factor is
MUAs that encourage top posting and quote entire messages without
making it clear that this is being done.

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

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