And then every so often mailman hits you up with "I'm receiving all these bounces from your email server!" because all the various garbage anti-spam techniques were not quite thought out with mailing lists in mind or people have lots of misconfigured servers and servers with different acceptance criteria, and it's all a big mess.
Configuring git send-email is only half the battle, anyway - chances are you want to participate in the discussion of your patch, so better figure out how to make sure your email client will not send the forbidden HTML email.