look into e-mail reply failures when responding to discussion notifications.
When members attempt to reply to discussion topic notifications, where the original message drops down and the message to "Reply above this line to add a comment" appears, the e-mail bounces back with the undeliverable response, "Your message wasn't delivered to email@example.com because the domain inbound.boardmanagement.com couldn't be found. Check for typos or unnecessary spaces and try again."
Members are aware they can log in to provide a discussion response; however, the e-mail response feature would certainly speed things up.
Chris shared this idea