thanks, was my mistake.
I corrected the code and it works now:

# send a mail when transfer completed
my $mail = new Mail::Sender
     {smtp => 'localhost', from => $linux};
    $mail->MailMsg({to => $recipient,
      subject => 'data transfer',
      msg => $content});
[download]

my second problem is, how to send a mail if transfer failed .
any idea ?