Have a user who has sent multiple emails but they are getting stuck in submission queue with the error : A storage transient error has occurred during content conversion. Tried rebooting server, no luck. Had user resubmit emails, but those ones got stuck in queue as well. Tried searching for that error online and got some info that exchange is having problem determining what the recipient can use for email content. Am stuck figuring out what needs to be done so these emails get to their respective recipients.