Re: st: RE: Hetero

[Phil Schumm <pschumm@uchicago.edu>]

On Jan 12, 2007, at 9:51 AM, Joanne Marshall wrote:
> Also, how can I reply under the thread so that my new message will  
> not appear as another thread? Sorry I have made the board look a  
> tad messy!

This question comes up a lot.  First, understand that the threading  
you see in the Statalist archives available on StataCorp's web site  
has nothing to do with the list (located and administered at Harvard)  
per se but rather with the software used to generate the archives  
(i.e., to generate the linked HTML pages from the messages  
themselves).  I'm only guessing, but from the footer on the archive  
pages it looks like the archiver being used is MHonArc.  This is only  
one of many such archivers out there -- one we used ourselves for a  
time.

MHonArc does its threading in two steps.  First, it attempts to  
thread messages based on the "In-Reply-To" header of the message,  
when present (it can also use a "References" header, which used to be  
added by some Internet news readers).  Your mail client generates  
this header when you use the "Reply" function.  This is by far the  
most reliable way to thread messages, and thus if the "In-Reply-To"  
header is present it trumps anything else.  This is why, when someone  
hits "Reply" to a message and then changes the subject, that reply is  
still threaded under the original message.

The problem, unfortunately, is that not all mail clients generate an  
"In-Reply-To" header, and in addition, I've heard that some mail  
servers are even configured to strip this header out when it exists.   
One of the two may be happening in your case, and if so, you may be  
able to rectify the problem by either (1) changing the configuration  
of your mail client, or (2) speaking with your local system  
administrator.

Second, if the "In-Reply-To" header is not present, MHonArc attempts  
to thread the message based on its "Subject" header.  It's pretty  
good about accounting for the various prefixes that get tacked on by  
the list (i.e., "st:") and/or by people's mail clients (e.g., "Re:"),  
and IIRC it has a few settings you can tweak WRT this, but sometimes  
when the different prefixes start to build-up it fails.  It's just  
plain difficult to intuit threads based on the subject line alone  
without taking into account the message content (and then it gets  
even more complicated).

The best advice for people who wish their replies to thread properly  
in the archives (and in people's mailers) is to try and make sure  
your mailer is adding the "In-Reply-To" header properly.  If that's  
not possible, then look in the archives to see which prefix  
combinations MHonArc is handling properly, and make sure when you  
post a reply your subject header contains one of these.

Hope that answers your question.


-- Phil

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