> conversation threading that actually works Gmail's "threading" is probably its worst sin (beating out its weird IMAP interface). When I started using Gmail,

> conversation threading that actually works Gmail's "threading" is probably its worst sin (beating out its weird IMAP interface). When I started using Gmail, my other mail client was mutt, but every other client at the time showed replies to email threads properly as a tree. As an aside, you could argue that email conversations should look like a DAG (since you could totally quote multiple emails and have multiple In-Reply-To headers, why not) but I'm not aware of any clients that did that. Gmail went a third way, completely linearizing a thread into a "conversation". This view makes it harder to have discourse over email: if you want to make sure to split a conversation and have both forks get addressed, you have to change the subject line to un-thread replies to your message.