Some time ago we set the For Sale forum to not allow any replies to a topic. While this solved the problem of "bumping" it also proved to be a genuine problem for some sellers, for the same reasons that Sandjam posted above. If a forum member does not have his email address in the Display Email field, there is no way to reach him other than an "Email Sent" post.
In other words, we can't please everyone on this situation because no matter which way we do it, we get complaints.
