I preface my comments by admitting that I am long retired from the CF and thus not familiar with the CF's current usage of electronic messaging. I'm sure that it is more widespread and less rigid in terms of who could communicate with whom than it was when I was serving. That being said, your primary examples are related to emails. To my aging Staff School trained mind, emails are the modern version of the memorandum, or more specifically, a round-trip memo. It is written communication, more informal than formal and traditionally would have been addressed to the "position". I would not have had any problem with receiving from subordinates emails addressing me as "Ops O", "Adjt", "DCO" or "CO" (all positions that I've held), or even being addressed by rank alone by someone outside my unit. In face to face conversation, however, if someone was deliberately avoiding calling me (or someone else entitled to that courtesy) "Sir", then they would be corrected, either by me immediately or by their Sgt Major after he received a call. Why are you only wondering if this is proper? Why haven't you corrected those who've strayed?