A strange thing started to happen couple weeks ago and I can't figure it out: some users receive some (not all) emails in plain text while others receive the exact same email in HTML. Is there a server setting that I can modify?
I've ruled out the AV possibility since I've uninstalled it on a user's workstation and the problem kept showing up. I've also uninstalled the AV on the server itself, for testing purposes, and nothing changed.
Thanks for your help on this one.