Emails from ETO can end up in your spam folder. This happened to me several times. My ISP would redirect them to a spam folder (on webmail) before I ever saw them in Outlook on my computer. Even after flagging the ETO address as non-spam, it still didn't seem to want to let them pass through. Never found out why this was happening on my end.. So, if ETO appears to be ignoring you, check your spam folders first, as you may find his responses sitting in there.