With all due respect to messaging and social networking, email remains the key form of business communication. It's been known to make or break deals. Often, it is not the content of the email, but rather, the sender's etiquette (or lack thereof). 

When using email so often throughout our business lives, we sometimes neglect the basic rules of communication: being polite, addressing people properly, responding in a timely manner, and more.

BCC is the perfect example of how email can be used effectively or completely abused. When using BCC, do we even think about what we're doing and how it can potentially backfire?

It's happened to me more than once. To save you some serious embarrassment, I'd like to address the issue here and now.

There are only two situations for the BCC.

First, mass emails. Rarely are they justified.

If you need to send one--you have a newsletter, for example, or you're sending out an invitation to your son's bar mitzvah--letting everyone see every recipient's email address is a huge no-no. Use BCC.

As an online writer, I often get pitches to my inbox, which are sent to hundreds (if not thousands) of bloggers and journalists. If you're a PR person, pay attention: This isn't the way to do PR, not even close. If, for whatever reason, you think that email is a good idea, use BCC. No journalist wants her email given to hundreds of other people she doesn't know.

If you don't use BCC in that scenario, you can expect to get blacklisted by a whole lot of journalists. Or family members who disagree with your bar mitzvah invite list.

Second, you absolutely must use BCC when someone introduces you to someone else. The person who made the intro did a nice thing, and shouldn't have to suffer through every response to that original email.

By BCCing that person, you're thereby releasing them from the emails that will follow. It's common courtesy and should be done 1-2 emails after their intro.

Beyond that, don't ever let others eavesdrop by using BCC.

In every other case, when you email someone and BCC someone else, you're being dishonest--like it or not.

You are emailing Person X and without them knowing, letting Person Y eavesdrop on your conversation. Person X has no idea that someone else is reading this email, when in reality, you secretly sent it to someone else as well.

Maybe this sounds like a small issue. It's not.

In business, integrity and transparency are your most important characteristics. If you're the type to BCC people on all your emails, you're not the type of person with whom I want to do business.

When people BCC me on emails, I immediately reply to them and tell them to please never use BCC like this again.

Which leads me to my next point: the dangers of BCC.

BCC can lead to a seriously awkward situation.

I once emailed a very high level executive at Google to recommend a friend for a job. I made the mistake of BCCing that friend to let him know I was sending that email.

Guess what my friend did? He accidentally replied all, saying, "Thank you." That meant the executive got an email thanking him from someone he didn't even realize was on the thread in the first place.

Who ended up looking really bad? Me. Who didn't get the job? My friend.

If you absolutely must, use the Forward button.

If you feel that the email you sent absolutely must be seen by someone else besides the recipient, forward it after you send it. It's slightly better than using BCC. I still don't recommend it, though.

By forwarding, you avoid the Reply All risk--but it's not a more honest move. You're still sharing private emails without one of the parties on the thread knowing.

Business ethics are everything. They begin with the way we communicate. Be the type of person you'd want to work with--not the type of person who makes you sweat with every email.