Instant Messaging Client Information

Currently the MSN Messenger is the only client that is able to connect to the Microsoft Exchange Instant Messaging Service. For a client to connect to Exchange Instant messaging it must support the RVP protocol. There are few versions of the MSN client available so let’s talk about these first

MSN Messenger Version 2.2

This client is provided on the Exchange server CD under the Instmsg directory. This is the simplest client available for IM and allows users to send text messages, invite another user to a Netmeeting and spawn a process to send an email. Installation and set-up of this client is very easy and no configuration needs to be done on users machines after installation.

MSN Messenger Version 3.6

This is the latest client that can be downloaded from Microsoft and provides the following additional functionality for Instant messaging users. Allows users to exchange files, start voice conversations and a Internet Telephone function. Installation of this client is still pretty straight forward there are more configuration options available to the users that should be configured through using smart scripting or GPO’s. If you want to use Outlook XP (2002) this version of the client or higher is required to activate the Instant messaging features of Outlook 2002.

Outlook XP (2002)

Office XP comes with a new version of Outlook(2002) which has Instant messaging functionality integrated within the application. The MSN messenger is still required to send and receive Instant messages. The new version of Outlook contains the following functionality. You can set-up Outlook contacts with IM addresses which when you receive mail from these contacts outlook will display their online status in the Info-bar, you can then click the infobar to start the MSN messenger to send them an Instant Message.

Deciding on the client

If you are heading down the Office XP path and you want Integration between Outlook and Instant Messaging the only way to go is with the latest client. The things that may worry network people are the ability to send files and start voice conversation. This could create a lot of unwanted Network traffic and could wreak havoc over a WAN to your bandwidth and usages charges

Client Configuration

Microsoft Q base article Q264472 give you all the information on what client options are configurable via the registry. I’m hoping in the future well see some sort of administration kit from Microsoft like the IEAK to lock down the application..

Internet Explorer proxy configuration

The IE Proxy configuration for the client is the most vital client configuration for Instant Messaging to work. The Instant messaging server you are using must be listed in the proxy exceptions (Make sure you use the FQDN ref Q242882). If this is not done then your IM will never work because all your requests will be going out via your proxy. If you’re tempted to reverse proxy using a product such as Novell’s boarder-manger remember you can't use NTLM if you’re going through a proxy. In this case you need to set-up digest authentication.

Non-Windows2000 Clients

For NT4 and Win9x clients to use Instant Messaging a requirement is to have ADSI 2.5 installed and the directory services client loaded. This enables these clients to support SRV name resolutions.

Roaming users

One main hurdle for the current IM client is the roaming users issue. The MSN Messenger client stores the users contact list for IM in the current users registry hive. Under Hkey_Current_User\Software\Microsoft\Exchange\Messenger registry key. This means unless your using roaming profiles when a user moves from one machine to another their contact list will not follow them.  Some solutions for this problem might be to, Implement a logoff script that saves the contact list to a file on the users home drive. Then at logon check for the existence of the contact list and if its not there create it from the file on the home drive. (Currently logoff scripts will only work under windows2K unless you implement a custom Gina on NT4). Another method is to use regedit to do an export/import of those registry entries

I have written some sample logoff scripts to do this have a look

Terminal Server

Unlike some Chat programs that have problems sharing IP/Port allocations Instant Messaging will work fine on Terminal Server. The main reason this may differ from chat is because IM uses a dynamic port allocation after the initial communication on Port80.

Status Lease

One of the jobs the Instant messaging client performs is maintaining the clients Status lease to the server. When a user logs onto IM they receive a status lease from the server and then the node database will start tracking that user as online. Every 20 minutes the client must renew this status lease. If this status lease is not renewed after 20 minutes the user will be considered offline. This can cause issues if users disconnect from the network without logging off properly, the online status for these clients will not be updated until the client’s status lease has expired.