The message-mail-alias-type variable controls what type of mail
alias expansion to use. Currently only one form is supported---Message
uses mailabbrev to handle mail aliases. If this variable is
nil, no mail alias expansion will be performed.
mailabbrev works by parsing the `/etc/mailrc' and
`~/.mailrc' files. These files look like:
alias lmi "Lars Magne Ingebrigtsen <larsi@ifi.uio.no>" alias ding "ding@ifi.uio.no (ding mailing list)"
After adding lines like this to your `~/.mailrc' file, you should
be able to just write `lmi' in the To or Cc (and so
on) headers and press SPC to expand the alias.
No expansion will be performed upon sending of the message---all expansions have to be done explicitly.