I like -- for mdash and === for separator: (setf org-export-html-special-string-regexps `( ("^-----$" . "<hr/>") ;see also === below ("---\\([^-]\\|$\\)" . "—\\1") ("--\\([^-]\\|$\\)" . "—\\1") ("^===$" . "<hr width=\"10%\"; style=\"width:10%;color:#000;background-color:#000;height:1px;border:none;\" />") ,@org-export-html-special-string-regexps))
-- The Kafka Pandemic: http://thekafkapandemic.blogspot.com