CODEWITHSUNDEEP
c#outlookc#-2.0office-interopoutlook-2003
Zerotoinfinity
Zerotoinfinity

Reputation: 6530

Unable to cast COM object - Microsoft outlook & C#

I have written this code to view the unread items in my outlook mail box and here is the code:

 Microsoft.Office.Interop.Outlook.Application app;
 Microsoft.Office.Interop.Outlook.Items items; 
 Microsoft.Office.Interop.Outlook.NameSpace ns; 
 Microsoft.Office.Interop.Outlook.MAPIFolder inbox;

 Microsoft.Office.Interop.Outlook.Application application = new Microsoft.Office.Interop.Outlook.Application();
        app = application;
        ns =  application.Session;
        inbox = ns.GetDefaultFolder(Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox);
        items = inbox.Items;
        foreach (Microsoft.Office.Interop.Outlook.MailItem mail in items)
        {
            if (mail.UnRead == true)
            {
                MessageBox.Show(mail.Subject.ToString());
            }
        }

but on the foreach loop I am getting this error:

"Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.Office.Interop.Outlook.MailItem'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{00063034-0000-0000-C000-000000000046}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE))."

Can you please assist me how to resolve this error?

Upvotes: 25

Views: 42513

Answers (5)

Shivam Ghai
Shivam Ghai

Reputation: 1

I ran into this problem because I had an email in my outlook folder which was delivery failed email.

Make sure you remove such mails from your folder and try again. For me, removing the email from the folder worked without making any changes in the code.

Upvotes: -1

Jeffrey DeMuth
Jeffrey DeMuth

Reputation: 139

Nice! adapted the solution a bit, this worked well for me

foreach (dynamic item in mailItems)
        {
            if (item is MailItem)
            {
                Response.Write("Sender: ");
                Response.Write(item.SenderEmailAddress);
                Response.Write(" - To:");
                Response.Write(item.To);
                Response.Write("<br>");
            }
        }

Upvotes: 1

KBoek
KBoek

Reputation: 5976

The following code worked fine when I tested it. But I must mention that my reference was to "Microsoft Outlook 14.0 Object Library". Do you happen to use another version?

    public class Outlook
    {
    readonly Microsoft.Office.Interop.Outlook.Items       _items;
    readonly Microsoft.Office.Interop.Outlook.NameSpace   _ns;
    readonly Microsoft.Office.Interop.Outlook.MAPIFolder  _inbox;
    readonly Microsoft.Office.Interop.Outlook.Application _application = new Microsoft.Office.Interop.Outlook.Application(); 

    public Outlook()
    {
        _ns    = _application.Session;
        _inbox = _ns.GetDefaultFolder(Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox);
        _items = _inbox.Items;

        foreach (var item in _items)
        {
            string subject= string.Empty;
            var mail    = item as Microsoft.Office.Interop.Outlook.MailItem;
            if (mail    != null)
                var subject = mail.Subject;
            else
                Debug.WriteLine("Item is not a MailItem");
        }
    }
    }

Please note that in Outlook, many items have some common properties (e.g. expiration time), so you can, as a desperate workaround, use a "dynamic" datatype - either as a fallback scenario for unknown item types or as your default (as long as you're fine with the performance hit).

Upvotes: 5

Anders Arpi
Anders Arpi

Reputation: 8397

I had to get around something like your problem a while back.

        foreach (Object _obj in _explorer.CurrentFolder.Items)
        {
            if (_obj is MailItem)
            {
                 MyMailHandler((MailItem)_obj);
            }
        }

Hope that helps.

The issue here is that _explorer.CurrentFolder.Items can contain more objects than just MailItem (PostItem being one of them).

Upvotes: 30

Bolu
Bolu

Reputation: 8786

try to check the item is a valid mailitem before checking its properties : 

foreach (Object mail in items)
{
    if ((mail as Outlook.MailItem)!=null && (mail as Outlook.MailItem).UnRead == true)
    {
        MessageBox.Show((mail as Outlook.MailItem).Subject.ToString());
    }
}

Upvotes: 9

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