use strict;
 my ( $dfrom, $dsubj );
 my $from = shift;

  while ( defined( $_ = <STDIN> ) ) {
      if ( substr($_,0,5) eq 'From:' ) {
         chomp($dfrom = substr($_,6);)
         last;
      }
  }

  if ( $dfrom && $from ne $dfrom ) {
       seek(STDIN,0,0);
       ... save copy and log ...
  }

  seek(STDIN,0,0);
  ... Clamav call by stream ...
  if ( ... virus found ... ) {
     ... warn mail ...
     exit;
  }

  seek(STDIN,0,0);
  open(AS, "| ... anti spam binary") or die " ... error string ";
  syswrite(AS, $buf) while ( read(STDIN, $buf, 32768) );
  close(AS);
  }