It's hard enough to make a good impression across email... so why would you deliberately make it worse by injecting sarcasm? Sure, you might just be kidding-- but the person on the other end doesn't know that. (Also, I don't think you should sarcastically insult anyone you barely know either... but apparently I'm weird that way.)
So... Here is the actual transcript of an email exchange with a guy who contacted me.
wow. that's pretty snarky.
plans on a sunday night...well then, aren't we miss popular
Can't, sorry. I have plans.
what about tonight? just go for a walk after dinner or something...
Yea, ok he may have been kidding. But frankly? This doesn' t make me want to go out with him. I barely know him and he's "teasingly" insulting me? Gee... What's it going to be like if we ACTUALLY start dating!? Can't wait for more belittling comments!