[grx]

> If you change the subject line, your email will get lost in my inbox since it will not be organized into conversations (I use gmail)

> Get your email program fixed, but do not change the subject.

That's strange. Threading should be based on the "References", "In-Reply-To" and related header fields, not on the subject. Maybe the emails your reader cannot organise, failed to supply the correct references. Gmail might then put an extra effort in it to match subjects, but this should not be the default case (and does not work in other clients).

[dvfjsdhgfv]

It used to be this way, but then Gmail appeared and changed the rules of the game. So these days you need to be aware that changing the subject line will appear as a new thread ("conversation" in Gmail jargon) for Gmail users. Which might not matter that much if you don't cut the previous e-mails that most e-mail readers append by default.