st: new postings versus replies to existing threads

[Phil Schumm <pschumm@uchicago.edu>]

A frequent admonishment on Statalist (as on other user lists) is to  
use an informative subject line when posting.  Many readers (myself  
included) are often forced, due to time constraints and/or high  
overall mail volume, to read the list by scanning the subject lines  
of new messages and ignoring those postings/threads on subjects that  
are not of interest.  As a consequence, failing to use an informative  
subject line risks failing to reach readers who might otherwise be  
interested in your posting and, just perhaps, in answering your  
question(s).

To this, I would like to add another piece of advice.  As many  
readers are aware, every email message carries in its headers  
something called a message ID (the exact name of the header is  
"Message-Id").  This ID is assigned by your mail server when you send  
a message.  Similarly, when you use the "Reply To" function in your  
mailer to reply to a message, the ID of the message you are replying  
to is put into a header called "In-Reply-To".  Not all mailers follow  
this standard, but many do.  This In-Reply-To header is then used by  
mailers that support threading to identify messages belonging to a  
particular thread.  Again, the details often differ across mailers,  
but several of the mailers I'm aware of work this way.

As a result, if you send a message to the list by replying to a  
previous message, your message may end up threaded underneath that  
previous message in readers' mailboxes, and therefore if they ignore  
the previous message as being uninteresting to them they may end up  
ignoring yours as well.  Note that this may happen regardless of  
whether you change the subject line, since that does not affect the  
contents of the In-Reply-To header.  It's true that some mail servers  
strip the In-Reply-To headers off messages that pass through them,  
and that some mailers will attempt to thread messages according to  
the subject header when an In-Reply-To header is not available.   
Moreover, the actual threading algorithms used by mailers are often  
complex and can make use of additional headers (e.g., References) if  
available, so it is difficult to predict behavior in any given case.   
Nonetheless, I frequently see instances on Statalist of a posting  
starting an entirely new thread (or asking a new question) which  
contains an In-Reply-To header corresponding to the ID of a previous,  
unrelated message.  And in my case, I miss such postings entirely  
unless I take the time to expand the corresponding thread and look  
through it.

In sum, I would urge those starting a new thread to do so by creating  
an entirely new message in their mailer, rather than replying to a  
previous message and simply changing the subject.  Such behavior is  
occasionally appropriate, as for example when continuing an existing  
thread under a new subject or forking a thread into sub-threads.   
Typically, though, what is desired is to start an entirely new  
thread.  Following this procedure will increase the chances that your  
question is read, and will make the Statalist archives more useful  
for all of us.


-- Phil

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