If you're actually reading email off LKML, that's another story.
But seriously: mutt, pine, Emacs mail mode, or even graphical clients such as Evolution or Kmail, will work just fine. And can be used in conjunction with nontechnical (there's another phrase I'm avoiding using here) GUI mainstream email clients used for other tasks.
If you can't figure out how to install and use mail / mailx / mutt with git, you probably shouldn't be submitting kernel patches. Which in this case is a useful filter.
[ed: never mind, my assumption was wrong:
git-am and git-send-email are used by some people. Submitting patches using those tools is just a matter of setting up the necessary parameters (email server and authentication information). But you can use any email client to participate in discussions about a patch series regardless of whether or not it mangles text (since review comments or further discussion obviously do not need to be applied to one's local copy of the code).