The more complex a message is, the more you need to consider which form of communication to use in order to convey it. Bill Howatt explains in an article for The Globe and Mail. When you have a big topic of conversation to convey, face-to-face communication (which includes video conferencing) is the best for making sure people understand it all. Ensuring that other people retain this information properly and communicate it back to subordinates is harder though. Written communication, like email, documents formally what needs to be done, but there is more room for ambiguity when people cannot get immediate clarification on any of the finer points. Howatt thinks the best thing a leader can do is create a routine out of sending short, written communications that efficiently notify people what is going on at a given time. Spoon feeding is a good way to convey information.
You can view the full article here: http://www.theglobeandmail.com/report-on-business/careers/management/how-to-ensure-employees-get-the-message/article10737193/