Be careful. Writing out steps to send email in the way the maintainers of the Linux kernel desire might be deemed as manspaining. You wouldn’t want to get blocked, would you?
The author already explained upthread that she knows how to do that and has a working setup to do so. But that process is onerous because LKML’s workflow is technologically backwards. (That’s my claim, not hers.) Assuming that someone with that kind of technical chops is too incompetent to Google “plain text gmail” is pretty disrespectful.