Encountering the same issue here. Not sure what changed to cause it. Appears to be impacting all of our Outlook 2016 systems, the older ones with 2007 appear unaffected right now. Can confirm that this only seems to be impacting html format emails as changing it to rich text allows them through without blanking out the body. I'll see if I can do some digging to find out if it was the ESET plugin that updated or Outlook that updated, but this seems like a result of something that likely patched in this morning.
