Problem with Outlook.OlBodyFormat.olFormatRichText

hello!

I have problem with setting RTF e-mail body format.
In my app I have a richTextBox control, and I want to set email body content from this richTextBox.

My source code looks like this:

...

Outlook.MailItem oMsg = (Outlook.MailItem)oApp.CreateItem(Outlook.OlItemType.olMailItem);

oMsg.BodyFormat = Outlook.OlBodyFormat.olFormatRichText;
oMsg.Body = richTextBoxEmailContent.Rtf;

Outlook.MAPIFolder oOutBox = oNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderOutbox);

oMsg.Move( oOutBox );

...

But in Outlook outbox folder this email is saving with all RTF tags in content.
Did Someone know what I have to do?

Please help me.