#e2ee is a goal, not a promise. As far back as I can remember, forums like those supporting #Enigmail and #gpg were staffed with volunteers from the privacy community who repeatedly insisted on answering questions, like, "Is <this> (whatever this might be) totally secure?" with stock questions like, "What is it that you consider 'totally secure?" or answers such as, "Secure is a relative term, nothing is completely secure, how secure do you need your mission's communications to be?"
Phrases such as, reasonably secure should be indicators of how ridiculous it is to assume that any secure platform isEVERcompletely, and totally secure.
That begs the question, "Exactly how secure do you require your communications to be?" The answer is always, ... relative.
Which means that you should always believe Ellen Ripley when she says, "Be afraid. Be very afraid!"