[Mimedefang] Filter did not remove UNFINISHED file

[Jason Englander]

Just a little tidbit for anyone else that runs into this...

My filter was ok (it passed mimedefang.pl -t, it was working most of the
time) but I was still getting the Filter did not remove UNFINISHED file
every now and then which would kick in 451 4.7.1 Please try again later
and all that.

I changed this:

  action_notify_sender(
    "The attachment '$fname' was deleted.  It contains a known virus.\n".
    "Here is the output from the virus scanner:\n$VirusScannerMessages"
  );

to this:

  if ($Sender && $Sender ne '<>') {
    action_notify_sender(
      "The attachment '$fname' was deleted.  It contains a known virus.\n".
      "Here is the output from the virus scanner:\n$VirusScannerMessages"
    );
  }

I think every one of the messages was a MAILER-DAEMON 'host
unknown' from AOL sent to an infected customer of ours.  $Sender on these
was set to <>, so when MD tried to notify the sender, sendmail tried to
send an e-mail to <>

  Jason