I've run into an issue with our install of QC 9.2 where whenever we try to send an email from within QC while the project is set to send HTML formatted emails, the send fails with a "Message refused" exception. However, if I change the email format to Text, the email sends fine. We're using Exchange to relay, but when the emails are in HTML format they don't even appear to be reaching Exchange (nothing in the spam filter, nothing in the message log). My guess is that there's something breaking the XML in one or more of our custom fields, but I'm not even sure where to start looking.

Has anyone run across this issue before? If so, how did you resolve it?