There are several users, including myself, who would like to be able to use the email gateway to reply to threads.
The email gateway is easily enabled, but you will need to either use a real email address as the sender to do this, or supply another email address in the Reply To field.
I would also like this, on my work breaks, it’s faster to reply to a post via email rather than having to open the link in the email, potentially logging in, then making my post, then going back to my email.