Never send anything on work email that you'd hate to see flashed up on a jumbotron.
Also, beware using the office internet. A former IT manager came down the pub one evening with a couple of print-outs and said "This is what xxxx is googling" (some guy in sales) - it was a list of searches like "how approach hot woman on train", "how approach hot woman in shop", "are asian women more friendly", "what does it mean if girl gives you a picture", etc. Then he called me a sick fuck for looking up "
kill your pet puppy".
Same IT guy disliked a girl who worked there so he'd skim through her work email, which she was foolishly using to chat to her boyfriend - or rather have a row with him, about some incident on the train that morning, where she hadn't held his hand. She was writing stuff like "Just because I didn't hold your hand, doesn't mean I don't love you," and her boyfriend was freaking out about how she'd stood on his left, not his right, so she saw the worst side of his profile - real BDD stuff. IT guy printed this off and brought it down the pub too. It felt too close to carcrash territory, but another co-worker thought it was hilarious and asked to keep the copy.
BUT...here's the kicker and life lesson...she split with her boyfriend and IT guy suddenly decided he really fancied her - so NOW the co-worker who laughed at her emails down the pub was on IT guy's shit list. Eventually, IT guy let slip that the guy was on betting sites half the day, so he got ousted. Just remember, workplace allegiances can shift at a moment's notice. You want to casually get on with everyone and don't get sucked into these mini-factions that tend to form and dissolve.
That girl became a vicar, by the way, no shit.