Well you guys are more hardline than me, good for you.
Personally, if a company wants to fire me for such transgressions as sending my wife an email that I’m running late, or forwarding a .pdf pay statement to my personal email because I have to access it on my company computer through the company portal, well I don’t want to work there anyways. I assume some back office IT guy can read everything I send on my computer, but that doesn’t mean I won’t erase personal correspondence upon leaving because then my boss or whomever will have access to it and that makes it more personal to me.