read outlook email c#4

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C#

C#4.0

Hello,
My windows application has a timer which every few hours reads my outlook inbox...
In the code I am using:

Microsoft.Office.Interop.Outlook.Application()

On my machine where I run this app. if I have my outlook open then the folowing code works

ns.Logon(null, null, false, false);

But, if I have outlook closed, then on that line above I get the following error even if I use the credentials i.e.

ns.Logon("domain\username", "pwd", false, false);

Could not complete the operation. One or more parameter values are not valid.

Questions:
1-
Eventually the idea is to have this app on the Prod. server so that it reads an email account which receives the required files to read...
How can I make the code to work without having outlook open?

Thanks