# Kitty - your client code.
#!/usr/bin/perl -w
use warnings;
use strict;
use IO::Socket::INET;
my $client;
my $server;
my $remote_port = 8100;
my $remote_host = "localhost";
my $line;


$server = IO::Socket::INET->new( PeerAddr => $remote_host,
                   PeerPort => $remote_port,
                   Proto    => "tcp",
                   Type     => SOCK_STREAM ) or die "Couldn't connect 
+to $remote_host: $!\n";

print $line = <$server>;

close $server;

# Server code.
#!/usr/bin/perl -w
use strict;
use IO::Socket::INET;

my $server_port = 8100;
my $client;
my $line;

my $server = IO::Socket::INET->new(

    LocalPort => $server_port,
    Type      => SOCK_STREAM,
    Reuse     => 1,
    Listen    => 10 ) or die

    "Could not create a tcp server on port $server_port : $!\n";


while( $client = $server->accept() )
{
  open( FH, "<data.txt" ) or die "Couldn't open 'data.txt' : $!\n";
  rand( $. ) < 1 and ( $line = $_ ) while <FH>;
  close FH;
  print $client "$line\n";
}
[download]

After outlining my dilemma in this node , the subsequent research lead me to a product that is being touted as a "MS Exchange Killer". The general sway of the project is to provide MS outlook clients with the necessary 'services' to leverage MOST of the groupware functionality that Exchange gives. Cost, scalability and performance are the areas that are its hilights.

Great toaster, so WTF is this all about then... OK - check out the information on Insight Server , Insight Connector and Insight LDAP Client, all at http://www.bynari.net. In simple terms, the two Middleware plugins for outlook (Connector and LDAP Client), are installed and configured to point to Insight Server.

The Server

• exim :

  Used as the MTA for the server it is responsible for relaying SMTP , and for local delivery of messages into the cyrusIMAP mailstore

• cyrusIMAPd :

  Rather than storing imap folders as one huge concatenated blob, cyrus is configured to stash mail in a simple database , keeping indexes etc - it's performance on a mailbox with thousands of messages is great so far - as I would expect. I'm not going to explain why/how - it's a database OK, the lookups are lookups not IO/CPU bound grep-to-death.

• openLDAP :

  all user information is kept in an LDAP accesible directory, it makes a real boon for the Outlook client to have a 'Global Addressbook' type access to the directory, authentication is also done using ldap (if you got nssldap and pamldap working - this is a walkover by comparison). In fact, I got so far as to have exim authenticate users before relaying mail on their behalf -as well as determining the existance of any locally addressed recipients.

The Plugins

• IMAP Mailboxes :

  Configure any number of IMAP mailboxes with local mappings to an Outlook .pst file . After initial configuration this button is basically lint.

• Mailbox :

  Allows you to configure the mapping of a single mailfolder to an IMAP server, I could for instance elect NOT to store my send messages on the server - unchecking a box here will do the trick.

• Folder :

  Popup panel for synchronisation settings and some very comprehensive ACL settings. The ACLs are mainly usefull for calender/appointment sharing, and those other things that executives and their assistants demand.

• Synchronize :

  Ahh the magic word, of course you can use the Folder panel to automagically sync each mailbox, but if you prefer manual-shift then bashing this button sets off the sync manager.




This is all well and good but now for the pain and heartache. If you're only comfortable with drag'on-slop GUI's for managing your users then Insight server is not going to make your life any easier. I have had success managing the LDAP directory with a little java applet, it's not feature rich, but gets the job done. As for administration of mailbox ACLs and whatnot, I suppose you could use cyrus's manager account to connect, since every mailbox defaults to full access for 'manager' and '$user'. So that makes outlook+connectors an administration interface.

Insight Server itself is about as well documented as your average sourceforge.net project, there are some PDF's covering the install and basic configuration but my advice is to read up on exim and cyrus...which brings me to those two jewels.

Exim - well, what can I say. If you can't absorb the reams of info in the Exim 4.10 Specification then not much can help you, I found 'Life With Qmail' a nice intro to digest before trying to understand the qmail docs, but was not lucky enough to find such a thing for exim. The docs seem comprehensive, providing you can find what you are looking for.

cyrus IMAPd has docs and manpages galore in the distro tarball, I have not played around much with it yet so that's all I'm saying about it.

SSL/TLS , I'm not a security nut and to say that it barely raises passing interest in this company is an understatement. Regardless I thought it proper to atleast give this a blast, in an afternoon I had cyrusIMAPd authenticating and serving mailboxes over autonegotiated SSL/TLS connections, to both outlook and also Netscape(4.79 IRIX!!). I forget if I mentioned already that InsightServer is a great plain-old-IMAPd as well, if you don't NEED outlook's groupware fluff then this'll still do a good job with your 5000 message imap folders.