(mapcar (lambda (rhs) (or (cadr (split-string rhs "@")) ""))
(mapcar 'downcase
(mapcar
- 'cadr
+ (lambda (elem)
+ (or (cadr elem)
+ ""))
(mail-extract-address-components field t))))))
;; Note that `rhs' will be "" if the address does not have
;; the domain part, i.e., if it is a local user's address.