Office Interop 32 bit on 64 bit OS email attachments filling up outlook temp folder OLK

Question

I have an issue when sending emails (many) using Office.Interop 32 bit that when the application is installed on a 64 bit OS the outlook secure temp is filling up and throwing an exception, this does not occur when the application is installed on a 32 bit
OS.
.NET framework 4.0
Visual Studio 2010 (C#)
Microsoft.Office.Interop.Outlook 14.0.0.0 Runtime v2.0.50727
for (int i = 0; i < 300; i++)
Microsoft.Office.Interop.Outlook.Application outlookApplication = new Microsoft.Office.Interop.Outlook.Application();
Microsoft.Office.Interop.Outlook._MailItem oMailItem = (Microsoft.Office.Interop.Outlook._MailItem)outlookApplication.CreateItem(Microsoft.Office.Interop.Outlook.OlItemType.olMailItem);
oMailItem.Recipients.Add("[email protected]").Type = 1;
oMailItem.Subject = "test email";
oMailItem.BodyFormat = OlBodyFormat.olFormatHTML;
oMailItem.Save();
oMailItem.Attachments.Add(@"C:\test_doc_1.docx", (int)Microsoft.Office.Interop.Outlook.OlAttachmentType.olByValue, Type.Missing, Type.Missing);
oMailItem.Attachments.Add(@"C:\test_doc_2.docx", (int)Microsoft.Office.Interop.Outlook.OlAttachmentType.olByValue, Type.Missing, Type.Missing);
oMailItem.Send();
Win7 32bit with Outlook 2010 32bit -> Works on this setup
Win7 64bit with Outlook 2010 32bit -> Does not work on this set up
Problem:
Sending many emails with the same attachment fills the outlook secure temp folder 
C:\Users\[User]\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\ZT7WMFGK\
(with a temp copy of the attachment) these files are not removed on Win7 64bit so at about 200 emails the exception is thrown:
"Cannot create file [file name]. Right-click the folder you want to create the file in, and then click Properties on the shortcut menu to check your permissions for the folder."
On Win7 32bit i can see the files getting automatically deleted from the secure temp folder so there is no problem
Im not sure where to start with this.

Answer 1

Seems that you have to release the objects explicitly. According to articles (http://www.bing.com/search?q=c%23%20release%20com%20objects), try this:
Application outlookApplication =
new
Application();
_MailItem oMailItem = (_MailItem)outlookApplication.CreateItem(
OlItemType.olMailItem );
var recipients = oMailItem.Recipients;
var recipient = recipients.Add(
recipient.Type =
1;
oMailItem.Subject =
"test email";
oMailItem.BodyFormat =
OlBodyFormat.olFormatHTML;
oMailItem.Save();
var attachments = oMailItem.Attachments;
var attachment1 = attachments.Add(
@". . . .", (int)OlAttachmentType.olByValue,
Type.Missing,
Type.Missing );
var attachment2 = attachments.Add(
@". . . .", (int)OlAttachmentType.olByValue,
Type.Missing,
Type.Missing );
oMailItem.Send();
Marshal.ReleaseComObject( attachment2
Marshal.ReleaseComObject( attachment1
Marshal.ReleaseComObject( attachments
Marshal.ReleaseComObject( recipient );
Marshal.ReleaseComObject( recipients
Marshal.ReleaseComObject( oMailItem );
Marshal.ReleaseComObject( outlookApplication
Check (with Debugger) that the files are removed at the end of this fragment.
Also consider creating a single outlookApplication before the loop.