How to close outlook after automating it in c#

Question

I am creating a program which converts Msg outlook file into pdf. What I did was export the Msg file into Html then convert the Html output to pdf. This is my code:

Microsoft.Office.Interop.Outlook.Application app = new Microsoft.Office.Interop.Outlook.Application();

string filename = System.IO.Path.GetFileNameWithoutExtension(msgLocation) + ".html";
string attachmentFiles = System.IO.Path.Combine(System.IO.Path.GetTempPath(), System.IO.Path.GetFileNameWithoutExtension(msgLocation) + "_files");
string extractLocation = System.IO.Path.Combine(System.IO.Path.GetTempPath(), filename);

Console.WriteLine(filename);
Console.WriteLine(attachmentFiles);
Console.WriteLine(extractLocation);
var item = app.Session.OpenSharedItem(msgLocation) as Microsoft.Office.Interop.Outlook.MailItem;
item.SaveAs(extractLocation, Microsoft.Office.Interop.Outlook.OlSaveAsType.olHTML);

int att = item.Attachments.Count;
if (att > 0)
{
    for (int i = 1; i <= att; i++)
    {
        item.Attachments[i].SaveAsFile(System.IO.Path.Combine(attachmentFiles, item.Attachments[i].FileName));
    }
}

app.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(app);

The MSG file convertion to HTML is working perfectly, but why is outlook.exe is still running? I want to close it, but app.Quit() doesn't close the app.

Answer 1

The issue is that the outlook com object is holding on to references and stopping the app from closing. Use the following function and pass your "app" object to it:

private void ReleaseObj(object obj)
{
    try 
    {
        System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
    }
    finally 
    {
        obj = null;
    }
}

See https://blogs.msdn.microsoft.com/deva/2010/01/07/best-practices-how-to-quit-outlook-application-after-automation-from-visual-studio-net-client/