But again no workflow. A good client understands and if necessary forces you to do the next thing. Say a mail has a web link. The sensible thing to do would be to store a fullpage screenshot with the email because web pages evaporate. Doing this with tools not designed for that specifically is so much work you shouldn't even bother to try it.

You want to reply? NO, YES, YES but not now. Then it should show up in the todo list. If the todo item only lives in "draft emails" it will get lost.