This article from The Mind Unleashed talks about how to prevent yourself from absorbing other people’s emotions: http://themindunleashed.org/2014/06/stop-absorbing-peoples-emotions.html
Those of us therapists who include notions of counter-transference & projective identification/introjection in our therapy work actually make use of clients’ emotional affects upon us…
…psychodynamic therapists use these phenomena to effect change in the client. We digest what unconscious emotional signals we “receive” from client (or what of our own emotional makeup may be triggered by the client’s story), try to understand it, then offer it (discretely) back to the client if the client is able tolerate it (and postpone further offers if the client rejects it).
This way of working comes from theoretical works published by Melanie Klein, Wilfred Bion, Donald Winnicott and others.
But – with the more skilled therapists – as a client you’d not be aware of this process going on, other than maybe noticing just how much your therapist seems to “get” you.