i wrote this in 10 minutes
(here in italy is night and i've got a good bottle of wine in front of me ;)))
stupid as you whant but fools netscape messanger :)
I used NetServer::Generic since is too late for me to mess with sockets...

#!/usr/bin/perl -w

use strict;
use NetServer::Generic;

my $server = new NetServer::Generic;
$server->port(25);
$server->callback(\&server);
$server->timeout(25); ## random...
$server->run();


sub server {

 open LOG, ">>/tmp/smtpd.log" || die "cannot open: $!";
 print LOG "\nNew connection\n-------------\n";
 print "220 mydomail.com ESMTP CianozMail 0.1 :)\n";
 while(<STDIN>) {
   print LOG "$_";
   if($_ =~ /^quit\r\n/i ) {
     print "221 Bye\n";
     close LOG;
     return;
   }
   elsif($_ =~ /^data/i ) {
    ## read message body here...
    print "354 End data with <CR><LF>.<CR><LF>\n";
    MESSAGE: while(my $line = <STDIN>) {

     if($line =~ /^\.\r\n/) {
           print "250 Ok: queued as ....\n";
           last MESSAGE;
     }
         else {
           print LOG "$line";
     }
      }
   }
   else {
     print "250 Ok\n"; #who cares? :-)
   }

 }
}
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