This class serves as the pool manager for NetFile request processor class
When an instance of this class is first created, a pool of request processor
instances are created.
SendFile will create a multipart message with the second
block of the message being the given file.
this demonstrates how to use the FileDataSource to send
a file via mail.
usage: java SendFile to from smtp file true|false
where to and from are the destination and
origin email addresses, respectively, and smtp
is the hostname of the machine that has smtp server
running.