(mail-names, mail-local-names, mail-directory-names)

(mail-names, mail-local-names, mail-directory-names)
(mail-address-field-regexp, mail-complete-alist)
(mail-complete-function, mail-directory-function)
(mail-directory-requery, mail-directory-process, mail-directory-stream)
(mail-directory-parser): New variables.
(expand-mail-aliases): Use `mail-address-field-regexp'.
(build-mail-aliases): Use space in buffer-name semantics.
(define-mail-alias): Reset `mail-names' to t.
(mail-complete): New command.
(mail-get-names, mail-directory, mail-directory-process)
(mail-directory-stream, mail-sentto-newsgroups): New functions.