Microsoft Interop Outlook c# - invalidcastexception? - interop

Question

Suddenly getting a System.invalidcastexception: unable to cast COM object of type 'system._object' to interface type 'Microsoft.office.interop.outlook.mailitem' ... to a program I wrote that was working fine and now BAM! Exception.
Not sure why... please note I'm a novice programmer.
Here's a snippet of coding where I'm using the Outlook things :
using Microsoft.Office.Interop.Outlook;
static Microsoft.Office.Interop.Outlook.Application app = null;
static _NameSpace ns = null;
static MailItem item = null;
static MAPIFolder inboxFolder = null;
static MAPIFolder dest = null;
static void SendMail(string mailSubject, string htmlMailBody, string mailTo)
{
Microsoft.Office.Interop.Outlook.Application outlookApp = new Microsoft.Office.Interop.Outlook.Application();
NameSpace outlookNS = outlookApp.GetNamespace("MAPI");
outlookNS.Logon(Missing.Value, Missing.Value, true, true);
MailItem oMsg = (MailItem)outlookApp.CreateItem(OlItemType.olMailItem);
oMsg.To = mailTo;
oMsg.Recipients.ResolveAll();
StreamReader sr = new StreamReader(#"C:\Users\" + WindowsIdentity.GetCurrent().Name.Split('\\')[1] + #"\AppData\Roaming\Microsoft\Signatures\Default.htm");
string signature = sr.ReadToEnd();
oMsg.Subject = mailSubject;
oMsg.HTMLBody = htmlMailBody + "<br><br>" + signature + "</font>";
oMsg.Save();
((Microsoft.Office.Interop.Outlook._MailItem)oMsg).Send();
oMsg = null;
outlookNS = null;
outlookApp = null;
}
app = new Microsoft.Office.Interop.Outlook.Application();
ns = app.GetNamespace("MAPI");
ns.Logon(null, null, false, false);
inboxFolder = ns.GetDefaultFolder(Microsoft.Office.Interop.Outlook.OlDefaultFolders.olFolderInbox);
#region match - convert - extract
foreach (string tifFile in Directory.GetFiles(workFolder, "*.tif", SearchOption.TopDirectoryOnly))
{
string currentFile = Path.GetFileNameWithoutExtension(tifFile);
for (int i = 1; i <= inboxFolder.Items.Count; i++)
{
//##############CODE CRASHES HERE##############
item = (MailItem)inboxFolder.Items[i];
// item = inboxFolder.Items[i];
if (item.Body != "")
{
if ((item.Body.Contains("Box Number =")) && (item.Body.Contains("Contract ID = ")) && (item.Body.Contains("Branch = ")) && (item.Body.Contains(currentFile.Replace('_', '/'))))
{
// matchFound = true;
MailStack current = new MailStack();
Console.WriteLine("________________________");
Console.WriteLine("File matched \t\t:\t" + currentFile + ".tif");
I've looked around but can't make much sense of the answers available.
any help appreciated.

Answer 1

Try this...
item = inboxFolder.Items[i] as MailItem;
if (item != null)
{
// ...
}