Clickable hyperlinks

Steve D'Aprano steve+python at
Wed Jan 4 05:08:52 EST 2017

On Wed, 4 Jan 2017 08:00 pm, Deborah Swanson wrote:

[speaking of threading emails]

> I suppose. Times change of course, which always suits some and not
> others. Personally, I think putting messages that have different titles
> all in one thread is a bad design, but as I've said a couple of times
> now I intend to comply with the new rules. But compliance doesn't imply
> agreement. I prefer the old system, which ordered threads by titles, but
> there's obviously no pleasing everyone on this issue.

Indeed :-)

However, as far as I am aware, the use of threading by following the
In-Reply-To and References header lines goes back to at least 1982, which
makes them pretty old, and certainly pre-dates Gmail and Outlook by many
years. They're also official standards which ALL email programs are
supposed to follow, so if Gmail and Outlook fail to follow the standard,
well, I wouldn't be surprised. I don't absolutely know for a fact that
threading in this way is older than threading by subject line, but I'm
fairly confident that what you are calling the "new rules" are actually the
much older rules.

Are there any old-timers here who were using email prior to 1982 that would
care to comment?

Here's a discussion by Jamie Zawinski, who wrote Netscape Navigator, before
it became Mozila and Firefox, so he knows what he's talking about:

The concept here is not so much that people start a new topic and change the
subject, but that sometimes the topic just naturally evolves to the point
that a change in subject is sensible. Take this thread for example: the
topic has drifted from "Clickable hyperlinks" to talking about email
threading. I should be able to change the subject without breaking the

Clickable hyperlinks
├─ RE: Clickable hyperlinks
│  ├─ Re: RE: Clickable hyperlinks
│  └─ RE: Clickable hyperlinks
│     └─ Threading [was Re: Clickable hyperlinks]
│        └─ Re: Threading
├─ RE: Clickable hyperlinks
└─ Re: Clickable hyperlinks

Adding a "Re:" or "RE" to the subject doesn't change the thread, and neither
does changing the subject line in a more substantial way.

Of course, I can always *choose* to sort by subject line, or date.
Personally I hardly ever sort by thread, so it is no skin off my nose what
you do. But when you hit "Reply" to a message, you inherit the "Reference"
and "In-Reply-To" headers from the previous message, so at least some
people will see it threaded in an existing thread rather than starting a
brand new one.

“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.

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