[Mailman-Users] pipermail+archives

Mark Sapiro msapiro at value.net
Sat Jun 25 20:43:34 CEST 2005

JC Dill wrote:

>Mark Sapiro wrote:
>> Jean-Philippe GIOLA wrote:
>>>I have seen in the list I use that these 2 headers are not all the times 
>>>existing, even if the mail that has been sent is an answer.
>>>Perhaps it depends of the MUA.
>> Yes, it depends on the MUA. The standard says these headers SHOULD be
>> included, not that they MUST be, so it is not wrong to omit them and
>> not all MUAs include them.
>This will also happen most of the time when the reply user is on digest, 
>because the digest has no reference header to the single article they 
>are replying to.  The exception may be if they are getting the digest 
>type that their email client can explode back into individual articles - 
>and if Mailman includes the reference header with the individual 
>articles.  Since I don't "do" digests, I don't know what the details are 
>with this type of digest and if threading works in this case or not. 
>Someone who knows more about this type of digest may be able to give 
>input on if it retains the references header for each post.

Yes. MIME format digests retain Message-ID:, References: and
In-Reply-To: headers from the individual messages so if the user's MUA
shows the individual message parts as separate messages that can be
separately replied to, and if the MUA properly creates References:
and/or In-Reply-To: headers in the reply, then threading will be

Plain text format digests retain the Message-ID: header, but not any
References: or In-Reply-To: headers from the original post. In this
case, a sufficiently aware MUA that can explode the digest could still
create an In-Reply-To: header in a reply that would allow proper
threading, but few if any popular MUAs can do this.

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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