We have gembox installed and recently updated the license for it. We have found that emails with standard fonts (.jpeg, .png etc.) does not work in the following scenario:
It is failing on the 2nd line - Object reference not set…
Document has data
So our theory is that the LoadOptions.HtmlDefault is not working.
if (!string.IsNullOrEmpty(inlineAttachments.BodyEndText)) document.Content.End.LoadText(inlineAttachments.BodyEndText, LoadOptions.HtmlDefault);