#!/usr/local/bin/perl

$debug=0;
$domainname="mns.net.au";
$hostname  ="mail.".$domainname;

$state=0;
$address="";
$offender="";
$message="";
$mode=1;

while (<STDIN>) {
	print $_ if ($debug>1);
	if ($state==0) {
	   # looking for content type or end of headers
	   if (/^Content-Type: /) {
		($junk, $boundary, $junk2)=split(/\"/);
		$boundary="--".$boundary;
		printf "boundary=%s\n",$boundary;
		}
	   elsif (/^Subject: /) {
		if (/ (.*)/) {  $subject=$1; chomp($subject);
				if ($subject =~ /^To: /i) { 
					$subject =~ s/^To: /To: /i;
					$mode=2; 
					}
			     }
		}
	   if (/^$/) { $state=1; printf "State=1\n" if $debug; }
	   }
	elsif ($state >= 1) {
	   # looking for boundary
	   if (/^$boundary$/m) {
		$state=2;
		printf "state=2\n" if $debug;
		}
	   }
	if ($state==2) {
	   if (/^Content-Type: message/) {
		$state=3;
		printf "state=3\n" if $debug;
		}
	   }
	elsif ($state==3) {
	   if (/^$/) { $state=4; printf "state=4\n" if $debug; }
	   }
	elsif ($state==4) {
	   if (/^$/) { $state=5; printf "state=5\n" if $debug; }
	   elsif (/^To: /) {
		if ($mode==1) {
		   if (/<(.*)>/) { $address=$1; }
		   elsif (/ (.*)/) { $address=$1; chomp($address); }
		   }
		elsif ($mode==2) {
		   $_ = $subject."\n";
		   }
		}
	   elsif (/^From: /) {
		if (/<(.*)>/) { $offender=$1; }
		elsif (/ (.*)/) { $offender=$1; chomp($offender); }
		}
	   $message .= $_;
	   }
	elsif ($state==5) {
	   $message .= $_;
	   }
	} # while STDIN

$time=localtime();

if ($mode==2) {
	$offender=substr($subject, 3);
	}

if ($debug) {
	printf "Offender: %s\nAddress: %s\n",$offender, $address;
	open (MAIL, ">/dev/tty");
	}
else { open (MAIL, "|-") || exec ("/usr/bin/sendmail", "-t", "-oi") or die("Can't access sendmail"); }

if ($mode==1) {
printf	MAIL "From MAILER-DAEMON\@%s  %s\n", $hostname, $time;
print	MAIL "Return-Path: MAILER-DAEMON\n",
	"From: Mail Delivery Subsystem <MAILER-DAEMON\@$hostname>\n",
	"Subject: Returned mail: User unknown\n";

printf	MAIL "To: %s\n", $offender;

print	MAIL "MIME-Version: 1.0\n",
	"Content-Type: multipart/report; report-type=delivery-status;\n",
	"        boundary=\"MAA21237.910759472/$domainname\"\n",
	"Auto-Submitted: auto-generated (failure)\n",
	"\n",
	"This is a MIME-encapsulated message\n",
	"\n",
	"--MAA21237.910759472/$domainname\n",
	"\n",
	"   ----- The following addresses have delivery notifications -----\n";

printf	MAIL "%s  (unrecoverable error)\n\n", $address;

print	MAIL "   ----- Transcript of session follows -----\n",
	"... while talking to $hostname.:\n\n";

printf  MAIL ">>> RCPT To:<%s>\n", $address;
printf	MAIL "<<< 550 <%s>... User unknown\n", $address;
printf	MAIL "550 %s... User unknown\n", $address;

print	MAIL "\n",
	"--MAA21237.910759472/$domainname\n",
	"Content-Type: message/delivery-status\n",
	"\n",
	"Reporting-MTA: dns; $hostname\n",
	"\n";
printf	MAIL "Final-Recipient: RFC822; %s\n", $address;
print	MAIL "Action: failed\n",
	"Status: 5.2.0\n",
	"Remote-MTA: DNS; $hostname\n";
printf	MAIL "Diagnostic-Code: SMTP; 550 <%s>... User unknown\n", $address;
print	MAIL "\n",
	"--MAA21237.910759472/$domainname\n",
	"Content-Type: message/rfc822\n\n";
}

print	MAIL $message;

if ($mode==1) {
print	MAIL "\n",
	"--MAA21237.910759472/$domainname--\n";
}

close(MAIL);