- (,(concat "^\\(" (regexp-quote mail-header-separator) "\\)$")
- 1 'message-separator-face)
+ ,@(if (and mail-header-separator
+ (not (equal mail-header-separator "")))
+ `((,(concat "^\\(" (regexp-quote mail-header-separator) "\\)$")
+ 1 'message-separator-face))
+ nil)