# Takes one file info, and returns a list of file infos for each file within the zip file.
# Since these are not directly MIME parts, they are simply:
#  {
#    name => $original_filename,
#    handle => $io_handle
#  }
sub _extract_zipfile {
   my ($file)= @_;
   my @files;
   my $zipfile= IO::Uncompress::Unzip->new($file->{handle})
      or die "Can't open zip file: $UnzipError";
   my $status;
   for ($status= 1; $status > 0; $status= $zipfile->nextStream()) {
      my $name= $zipfile->getHeaderInfo->{Name};
      $log->info("Extracting $name from zip file");
      my $tmp= File::Temp->new(TEMPLATE => 'email-zip-content-XXXXXXX');
      my $buf;
      while (($status= $zipfile->read($buf)) > 0) {
         $tmp->print($buf) or die;
      }
      last if $status < 0;
      push @files, { name => $name, handle => $tmp };
   }
   die "Error processing zip file"
      if $status < 0;
   return @files;
}