Batch Sender is a command line tool, that can run on Windows (DOS), Solaris, Linux, AIX, HPUX (if you need we can make a special executable for other OS like Mac OS X, SCO, BSD, IRIX, Tru64, ...) in the same way.
You need an SMTP host (in your company o in your ISP). With Batch Sender you can use SMTP to send batch emails.
Batch Sender is the program you are looking for if you have an old script, program that works in every OS and you'll need too much time to develop the email support.
Batch Sender is chip and powerful.
It supports notify and priority. You can use STDOUT of your own applicaton to fill the body field.