Ask HN: Are there any tools to diagram long email chains?

It turns out that I have been missing some important background on long email chains.

When my directors have a 1-on-1 conversation with each other, then loop me in, Gmail threading mode seems to suppress the messages that I wasn’t a recipient to.

This has been an ongoing problem for me, but now I’m stuck trying to sort through the extra crumbs left behind, when recipients change on reply/forward and it’s starting to get really annoying.

Are there any tools out there to draw a diagram or organize my email chains in any better format?