Get and sign in to an instance of Outlook

This topic shows how to obtain an Application object that represents an active instance of Microsoft Outlook, if there is one running on the local computer, or to create a new instance of Outlook, sign in to the default profile, and return that instance of Outlook.

Example

The following code examples contain the GetApplicationObject method of the Sample class, implemented as part of an Outlook add-in project. Each project adds a reference to the Outlook Primary Interop Assembly, which is based on the Microsoft.Office.Interop.Outlook namespace.

The GetApplicationObject method uses classes in the .NET Framework class library to check and obtain any Outlook process running on the local computer. It first uses the GetProcessesByName method of the Process class in the System.Diagnostics namespace to obtain an array of process components on the local computer that share the process name "OUTLOOK". To check whether the array does contain at least one Outlook process, GetApplicationObject uses Microsoft Language Integrated Query (LINQ). The Enumerable class in the System.Linq namespace provides a set of methods, including the Count method, that implement the IEnumerable<T> generic interface. Because the Array class implements the IEnumerable(T) interface, GetApplicationObject can apply the Count method to the array returned by GetProcessesByName to see whether there is an Outlook process running. If there is, GetApplicationObject uses the GetActiveObject method of the Marshal class in the System.Runtime.InteropServices namespace to obtain that instance of Outlook, and casts that object to an Outlook Application object.

If Outlook is not running on the local computer, GetApplicationObject creates a new instance of Outlook, uses the Logon(Object, Object, Object, Object) method of the NameSpace object to sign in to the default profile, and returns that new instance of Outlook.

The following is the Visual Basic code example, followed by the C# code example.

If you use Visual Studio to test this code example, you must first add a reference to the Microsoft Outlook 15.0 Object Library component and specify the Outlook variable when you import the Microsoft.Office.Interop.Outlook namespace. The Imports or using statement must not occur directly before the functions in the code example but must be added before the public Class declaration. The following lines of code show how to do the import and assignment in Visual Basic and C#.

Imports Outlook = Microsoft.Office.Interop.Outlook

using Outlook = Microsoft.Office.Interop.Outlook;

Imports System.Diagnostics
Imports System.Linq
Imports System.Reflection
Imports System.Runtime.InteropServices
Imports Outlook = Microsoft.Office.Interop.Outlook

Namespace OutlookAddIn2
    Class Sample

        Function GetApplicationObject() As Outlook.Application

            Dim application As Outlook.Application

            ' Check whether there is an Outlook process running.
            If Process.GetProcessesByName("OUTLOOK").Count() > 0 Then

                ' If so, use the GetActiveObject method to obtain the process and cast it to an Application object.
                application = DirectCast(Marshal.GetActiveObject("Outlook.Application"), Outlook.Application)
            Else

                ' If not, create a new instance of Outlook and sign in to the default profile.
                application = New Outlook.Application()
                Dim ns As Outlook.NameSpace = application.GetNamespace("MAPI")
                ns.Logon("", "", Missing.Value, Missing.Value)
                ns = Nothing
            End If

            ' Return the Outlook Application object.
            Return application
        End Function

    End Class
End Namespace

using System;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;
using Outlook = Microsoft.Office.Interop.Outlook;

namespace OutlookAddIn1
{
    class Sample
    {
        Outlook.Application GetApplicationObject()
        {

            Outlook.Application application = null;

            // Check whether there is an Outlook process running.
            if (Process.GetProcessesByName("OUTLOOK").Count() > 0)
            {

                // If so, use the GetActiveObject method to obtain the process and cast it to an Application object.
                application = Marshal.GetActiveObject("Outlook.Application") as Outlook.Application;
            }
            else
            {

                // If not, create a new instance of Outlook and sign in to the default profile.
                application = new Outlook.Application();
                Outlook.NameSpace nameSpace = application.GetNamespace("MAPI");
                nameSpace.Logon("", "", Missing.Value, Missing.Value);
                nameSpace = null;
            }

            // Return the Outlook Application object.
            return application;
        }

    }
}

See also

• Sessions