Those angels who are wisest and most experienced are Men who have been born, lived, died and been resurrected: these are the post-mortal angels, and are Man's greatest spiritual teachers.
Post-mortal angels can communicate with us by the usual means of communication - spoken, visual, by writing etc - but of course (in the modern West, especially) such communications are prone to inattention, misrepresentation, misunderstanding; and are quantitatively utterly swamped by the mass media, government and corporate propaganda, trivial and dishonest social interactions and many other net-evil communications.
Therefore, the post-mortal angels also use direct knowledge, in the universal realm of reality. This is the 'underworld' realm which Man spontaneously but passively and unconsciously accesses in early cultures, early childhood and in sleep. But in such circumstances, the knowledge is not explicit and we are unaware of it except as feelings.
For modern Man, feelings are not enough - even if those feelings are broadly benign. For modern Man we must know - and know that we know - and what we know must be thought so that it may be integrated with all other knowledge.
(That is after all, the divine way of being - God knows everything explicitly, not as instinctive urges and aspirations.)
So - what the post-mortal angels need to tell us is incorporated into the universal realm of reality; and we can each of us know it IF we can think in such a way that we too are thinking in this realm. This is what I have termed Primary Thinking, which is the conscious and purposive intuitions of our true self.
However, modern Man does very little thinking with his true self, instead functioning mostly from a variety of superficial, labile, automatic, inculcated ways of 'processing' information... And when modern Man does think with the true self, then his modern metaphysics tells him that such thinking is meaningless, subjective, 'wishful thinking' or delusional.
However, THAT is where the knowledge of the spiritual teachers of Man is located - and if we want to know it (rather than merely to feel it) then we need to engage in Primary Thinking, and take it with the utmost seriousness.
So... the first message of the post-mortal angels is the two-fold information that Primary Thinking is necessary, and that it is primary... In other words, that this is what we most need to do; and that if and when we can achieve primary thinking it will become our primary basis for living - ultimately superseding all external forms of communications from authorities (including from churches).
We are to base ourselves and our lives upon our own, personal direct knowledge of reality; and not not secondhand/ communicated/ interpreted knowledge.
The second type of information involves hints as to what we will discover. This is already known, from the writings of prophets - but that is not sufficient, because we need to know it for ourselves and directly.
But what we will discover is that all Men are a family, we are all actual (not symbolic) brothers and sisters because we are actual children of God - who is therefore our Parent... or rather parents: Father and Mother. God, the creator, is our loving Father and Mother. This is absolutely vital knowledge without which we cannot understand anything of importance - and we each need to know it directly, not as an hypothesis.
This information also means that we are all divine, of God-nature; but embryonically so. We are flawed and immature Gods; but Gods we indeed are.
Furthermore, we are (potentially) even more closely spiritually-connected into families and 'clans' - our blood relations, our married spouses, and even (that rarest of rare relationships) our true friends may spiritually be bound by commitments of voluntary and mutual love. We are therefore connected in multiple ways, really connected. We are not alone: we are never alone.
This is a modern revelation - not to be found in the ancient scriptures; because it is an insight from the lives of post-mortal angels, our closest spiritual teachers; and results from their experiences in relatively-recent lives (past few hundred years), which have taught them the necessity of this truth.
Now, all this is vital and urgent knowledge, and will lead to a transformation of earthly life. But of course it will not lead to Heaven-on-Earth because we don't treat our known spouses, families and real-friends perfectly well... we are only flawed, incomplete, partly-grown gods.
Why am I saying this, as a mere 'communication' - with very limited distribution, prone to incomprehension and misunderstanding? The answer is that by knowing these things first as 'hypotheses' - some people may be encouraged to seek their validation: to look for them by seeking the reality-of and developing their ability-at Primary Thinking.
(Don't believe Steiner, don't believe me: take these insights as hypotheses - then find-out for sure, for yourself.)
And then they may find some or all of the hypotheses confirmed and clarified by their personal intuitions - which is the only thing that can make them real, and provide a solid basis for Life: for Life as it should-be.
NOTE: The above is a re-explanation, with what I regard as corrected metaphysics, of the content of Rudolf Steiner's 1918 prophecy - usually published with a title something like The Work of the Angel/s in Man's Astral Body. I have also added what I regard as the core of Mormon teaching, the vital essence of what Mormonism has added to Christian doctrine, and which is ever-more necessary for us to grasp (something of which Steiner, knowing nothing substantive of Mormonism, was unaware).