How to avoid multi logging of MAPI

Hi there,
Thankyou for sparing sometime for my query.
Actually I have developed a COM Application which has the following components.
1) A COM Server
2) A Client-GUI applicaiton.
I have used 'new'operator to create my COMServer object in my Client application and Iam using the methods of the COMServer.
Now in my COMServer, Iam using a Win32 DLL crearted inVC++, which has soe customized MAPI APIs.(like Logon, SendMAil etc...)
I have created the Setup files of both COMServer and Client-GUI application. Now when I install the ClientGUI on any machine and start my application then it is also invoking then Outlook express of the Client machine.
In my Server, once the object is created then my application is invoking the Outlook applcation and I logon to the Admin ID on the server. Then the COMServer Object is created successfully on the Server machine.
After this once I start the client application then on the client machine also it is invoking the Outlook express to be logged on to the local user's mail id. But I don't want this to happen.
In my COMServer..... I have.....
InitMAPI()----- A call to the API of the DLL which I wrote in VC which calls the INITMAPI() API of MAPI.H.., and then I call Logon() in the VB which invokes MAPILOGON() of MAPI.H
My DLL is written in VC, and COMServer (ActiveEXE) is written in VB and ClientGUI is also developed in VB.
If the description I gave is insufficient then please mail me so that I can still give a better picture of my application.
Please suggest me some solution to this problem. Since it also involves a bit of VC, hope you folks don't mind putting this query in this forum.
Thankyou once again and I will be looking forward to have your valuable suggestions.

Best Resgards
Suku