I see many managers delivering bad news via email, because it is more comfortable for them. Twitter making mass redundancies via email is one such example.
The trouble is, it may be easier for you as a leader – but its far worse for the individual and the company culture.
When there is bad news, or difficult feedback to give: do it in person, face to face. You manage the tensions there and then, its honest, and there is crystal clear clarity which cannot be misinterpreted.