True, it doesn't protect from every threat model in existence, I've been considering setting up some kind of third party reflector model, but the problem there

True, it doesn't protect from every threat model in existence, I've been considering setting up some kind of third party reflector model, but the problem there is that the termination point for the plaintext recipients still requires trust at some level. I recognise this isn't perfect, but the very fact that in various stories a fuss has been raised about data retention times indicates it might not be completely useless to close the window of vulnerability, another comment in this thread mentions monitoring the incoming messages via IMAP IDLE also which is another idea, but once again there is a non zero window of plaintext messages on the server. And if nothing else, the thousands of spam messages this will armor with strong encryption will give the fascists something to waste their time on.