Yes, as azurelunatic suggested, you can give each of your icons a secondary keyword for emailed-comments use, and specify those when you're replying by email -- comments can have more than one keyword. (I also opened up a bug today for letting you get an emailed version of all your icons + keywords, like the /icons page, that will allow you to keep it in your inbox to have it handy for a reference, but that almost certainly won't be done before Monday's push.)