openstreetmap-website/app/views/message/mark.js.erb

$("#inboxanchor").replaceWith("<%=j render :partial => "layouts/inbox" %>");
$("#inbox-count").replaceWith("<%=j render :partial => "message_count" %>");
$("#inbox-<%= @message.id %>").replaceWith("<%=j render :partial => "message_summary", :object => @message %>");