& mail-folders

  The MUX mail system allows each player 16 folders, numbered from
  0 to 15. Mail can only be in 1 folder at a time. Folder 0 is
  the "inbox" where new mail is received. Most @mail commands
  operate on only the current folder.

  @mail/folder
        This commands lists all folders which contain mail, telling
        how many messages are in each, and what the current folder is.

  @mail/folder <folder#|foldername>
        This command sets your current folder to <folder#>.

  @mail/folder <folder#> = <foldername>
        This command gives <folder#> a name.

  @mail/file <msg-list>=<folder#>
        This command moves all messages in msg-list from the current
        folder to a new folder, <folder#>.
