“Some people just don’t care about their customers,” my friend Aileen snapped. “I’m ready to dump this vendor and find someone else!” She was fuming – and it was all because of a common e-mail mistake.

The e-mail hadn’t been sent to Aileen. “Jennifer,” a wedding cake baker, had sent the nasty e-mail to Aileen’s wedding coordinator. (If you’re curious, the e-mail said something like “Your Oct. 4 client wants what? Is she nuts?”)

And the wedding coordinator had included that e-mail in the one she sent to Aileen.

I’m sure the wedding coordinator wasn’t trying to cause problems. She just didn’t think before forwarding the e-mail to Aileen. And I’m equally sure that Jennifer wasn’t trying to be malicious. In fact, I bet if she’d known that Aileen would see her e-mail, she would have chosen her words much more carefully.

E-mails – especially forwarded e-mails – can be misinterpreted …and possibly even ruin your career.

It’s so easy to click “forward” on an e-mail – or to copy someone else when you reply to the sender – that you may forget that you could be breaching someone’s privacy… or passing on sensitive information… or inadvertently making waves.

As Michael Masterson says, “Forwarding someone’s e-mail without asking his permission is impolite and potentially troublesome.” So keep these three alternatives in mind:

1. Whenever you feel the urge to forward on an e-mail, stop. Start a brand-new e-mail. And paraphrase the other person’s relevant comments.

2. When you forward an e-mail, delete EVERYTHING from it that’s irrelevant. For instance, a friend e-mails you… and mentions that she’d like to be a speaker at your upcoming conference. You forward your friend’s request to your event director – but first you delete her recap of last weekend’s cocktail party.

3. ASK. It’s super-easy to ask your friend/colleague/potential partner if you can forward their e-mail to someone else.