I'm back from vacation and wading through e.mails, voice mails, etc. At these times, there is a temptation to be curt, in order to blow through the stack as quickly as possible.
Here is why you shouldn't.
I got a series of someone else's e.mails by mistake. I'd responded early on with an "unsubscribe" for that list, but I kept getting them. They accumulated over the past few weeks, and today, I see that there was some time-critical information in them.
It wasn't a big deal, not like something redirected from Bill.Gates@microsoft.org (Subject: Operation Armageddon - final status update), but I could see how the intended recipient might be upset at missing the info.
I responded, explained, and suggested they get the right contact info and redirect. I got a quick response affirming, explaining and closing out the issue. A friendly back-and-forth afterwards, and that was that.
I won't get e.mails I don't want, the intended recipient will get the info they need, the sender won't be wondering why what's-his-name never responded to the e.mails. It's a win-win-win.
Could I have achieved the same result by being a jerk about it? The distance and lack of relationship would have made it easy. Sure, but this way, I feel good about myself. I made a tiny cameo appearance in someone else's life and, if they retain any thought about me at all, it will be neutral to positive. If I'd been an ass about it, they certainly would think of me, and not at all kindly.
The long and the short of it is, when given the opportunity to either contribute to civility and harmony or to detract from it, you should try to make things better. You will be a better person for it.