In 1971, a computer engineer named Ray Tomlinson sent the very first email: a test message to himself, which he sent to a computer placed right next to the computer he used to send his message.

Today, more than 269 billion email messages are sent every day, according to the Radicati Group. That's about 72 emails for every one of the estimated 3.7 billion email users in the world.

A lot of this email is generated at work: Companies just can't run without it. The global economy would grind to a screeching halt if email traffic were to suddenly stop.

But how much of these billions of emails that are sent each day actually achieve what the sender set out to accomplish? What is the impact on employees' productivity, professional growth, and even emotional health of reading so much email each day?

These questions await a comprehensive scientific study. But in the meantime, here are six email habits I continue to observe that, I argue, chip away at productivity, stunt professional growth, and even might cause emotional harm to some of the folks on the receiving end of such email behavior:

Here goes:

1. Addressing multiple people in an email request that can be answered by just one person.

Ever get an email addressed to you like this? "Dear person A, person B, person C". The sender assumes one of you knows the answer to the question or has a solution to the problem they raise in the email. Since it's easy to type two, three, or more names, why not carpet bomb them all at the same time and save the trouble of trying to find out who is best placed to actually help?

Sure there are instances where you want to share information with several people simultaneously. But that's sharing information. When you want to solicit someone's help, asking three or more people at the same time and in the same email confuses and also sends the message that you really don't know who you should send the email to.

2. Sending the same email request separately to multiple people without telling the others.

I've seen too many aggressive salespeople (or others who are trying to secure time and attention from me or my colleagues) over the years make the same exact pitch to multiple people from the same company, but without copying the others on their email. It's a numbers game, right? Just blast as many emails as you can and surely, the odds will eventually favor you and will yield a positive reply, right?

No, that's not how it works.

3. Unnecessarily bringing other people into an email that was addressed solely to you.

I sent an email to you asking you for your opinion or advice on a matter that is relevant to you. So why did you bring in someone else or even multiple people into the email thread? It's like I'm at a cocktail party having a one on one conversation about a personal matter and then you suddenly invite two more friends to answer the question I had just posed to you in confidence. Okay, so I exaggerate. But that's how it feels when you add others in your reply to the email I had only addressed to you.

Before inviting others into an email conversation, ask the person, or just don't do it.

4. Demanding someone do something or reply to you "ASAP".

A couple of problems with the use of "ASAP." The most obvious of these is that it makes you look like a drill sergeant barking a command to a hapless new soldier in boot camp training. Doesn't exactly leave a warm and fuzzy, let's-work-as-a-team feeling, does it?

The other thing about the use of "ASAP" is that it looks like you're shouting. Anything written in all capital letters looks like you're screaming on the screen.

5. Asking for a favor in the very first email that you've ever sent to someone.

"Hello, I found you on the internet (or on LinkedIn) and thought since you're probably not very busy, and you have never heard of me before, and therefore have no basis for trusting me yet, that you could help me find a job at your company, or introduce me to some of the folks in that valuable professional and personal network you've spent years to establish."

Of course, nobody ever phrases their message in exactly these words when they cold call me by email or through LinkedIn. But that's precisely the message they send when they start asking for something from the very first email they send.

6. Asking for someone's time without any clear (or implied) benefit in return.

"Can I pick your brain?" "Can we setup a quick call on Skype?" "Could we meet for coffee?"

I get these questions frequently, sometimes at work, and often through LinkedIn. Don't get me wrong: I like to help others. And, sometimes, I am pretty helpful to others without expecting (or getting) anything in return.

But I'm also very busy at work. And I've got my family I need to take care of and spend time with. What time is left, I like to devote to my hobbies, like blogging and podcasting. I must, therefore, prioritize my time very rigorously.

So if you're going to ask for my time or want to know what I know about a topic that interests you, I might provide a quick answer, and I might try to help. But if it's not clear what I will get from our chat besides the warm and fuzzy feeling I get from helping others, then I'll need to place your request in its appropriate position on my list of priorities.