From: Jacob Fugal <lukfugl@...>
Date: 2006-06-16T06:47:53+09:00
Subject: Re: Why do my posts appear twice?

On 6/15/06, Jeremy Tregunna <jtregunna@blurgle.ca> wrote:
> On 15-Jun-06, at 2:32 PM, Austin Ziegler wrote:
> > It's a Gmail glitch.
>
> I'd have to be a little weary about that statement. I see this exact
> same behaviour using Mail on OSX 10.4 from my own mail server -- none
> of my other lists or whatnot experience this same problem, only ruby-
> talk. However, in my case, it's *all* messages to ruby-talk get sent
> twice, not just my own.

In your case, it's probably because you're double subscribed or
something. Not at all the same problem. Regarding the OP's problem, I
can indeed verify that it is a gmail "feature". When I post to
ruby-talk using my gmail account, I also see the post duplicated. From
the beginning I suspected this was a gmail thing, and believed it when
others suggested that too. But for the sake of completeness, I
investigated.

For every email in a thread in gmail, you can click the "More options"
link to see a little more detail about the headers for that email. If
that's not enough, from within the "More options" block, you can click
"Show original" to see the email in all its plain text glory, headers
intact.

Going to a thread to which I've posted, I see the two "duplicate"
emails one right after the other. Clicking "More options" for both, I
can see that the first email I see has a "To:" and a "From:", while
the second has a "To:", "Reply-To:" and "From:". The "Reply-To:" for
the second is set to "ruby-talk@ruby-lang.org", just as it is for all
other emails from the list. This is because the ruby-talk list
software does what is commonly known as Reply-To munging. *Every*
email that comes from the list has this Reply-to header. But the first
copy of my email does not -- it *can't* have come from the list. So
where did it come from?

Look over to the right hand side in that "More options" box, there's
the value of the Mailed-By header. Guess what, for every email from
the list, including the second copy of my email, it says
"ruby-lang.org". But for the first copy, the Mailed-By header is
"gmail.com". In other words, it is the email that was *sent* by gmail,
not one you *received*.

Need further evidence? Go to your "Sent Mail" folder. Choose a
ruby-talk thread and click on it. What's the first unfolded message it
shows? That's right, the first copy of your email, which is embedded
right into the thread. It opens to that one because it's the one you
*sent*.

In short, you see two copies of your email in the thread because gmail
shows both the original sent copy along with the copy you received
from ruby-talk.

I don't call this a glitch or bug in gmail, since it's useful behavior
for most circumstances. Most people using gmail probably don't CC
themselves when they send an email out, so if they want to see their
email included into the thread, it makes sense to show the sent copy.
But when the mailing list sends you a copy of its own, you see a
"duplicate". That's all that's happening. If it's not happening for
other lists, it must be because they aren't sending you a copy of your
own messages -- which is perfectly fine. It's just that ruby-talk's
default is different, and you *can* change it if you want.

Jacob Fugal