When trying to export a document which contains hyperlink pasted from Outlook, KeyNotFoundException is thrown. The color of the span is not registered.

To work around this, register a style with the same color:

StyleDefinition style = new StyleDefinition("test", StyleType.Character);
style.SpanProperties.ForeColor = Color.FromArgb(100, 200, 25, 104);
this.radRichTextBox.Document.StyleRepository.Add(style);