Usage:
MESSAGE conf:integer, to:string, from:string, subject:string, sec:string, msgdate:date, retreceipt:boolean, echo:boolean, file:string
Write a message in conference “conf”, to user “to” (empty string defaults to current caller), from user “from” (empty string defaults to current caller), subject “subject”, security in “sec” (N or R; N is the default), pack out date in “msgdate” (0 for no pack out date), “retreceipt” True if return receipt desired, “echo” TRUE if message should be echoed, and “file” is the filename to use for the message text