How to post from email

I keep getting this response.
We’re sorry, but your email message to [“”] (titled : Re: 6 digit node Numbers) didn’t work.

The category you sent this email to only allows replies from users with valid accounts and known email addresses. If you believe this is an error, contact a staff member.

Well even that sent it’s self before I finished typing. Is this system so convoluted that you have no general email address people can ask a question to without vising a web page on some PC?