Having made a 12-year run in B2B sales earlier in my career, I've seen a lot of deals go sideways for various reasons. However, this particular one I will never forget. Not only was the dollar amount of the deal huge, but the way it was lost will forever resonate with me.

Instant messaging services like Slack have risen in popularity in many businesses as a way of quick internal communication.

However, when it comes to communicating with customers, email is still the primary method, especially within B2B.

At some point in time, everyone has been a part of a damaging email blunder. Some are worse than others.

My experience with an email blunder came when I was an account manager for a high-profile national account. The account was large enough that it took a team to manage it.

The contact whom we dealt with for the client was often hard to work with and extremely demanding. One day we received an email from the client with some pretty demanding requests that we needed to get to right away to meet their needs.

Our team leader in the customer care department sent out an email that was meant only for our internal team. However, she forgot to remove the client. A minute later there was a frantic attempt to recall the email. Too late: It had gone out to the customer. The email read:

"The wicked witch of the west is back on her broomstick. Which one of you wants to respond?"

The employee who sent the email was terminated. A formal apology letter was issued to the customer that let them know the employee had been terminated.

It was too late. We were already on the fence with this customer as far as being able to renew their business. The offensive email to their most influential decision maker was the straw that broke the camel's back. We were out as their provider. The customer moved millions of dollars of business to a competitor when their agreement with us expired.

Here are tips to keep in mind when sending out business emails that will prevent you from losing a deal, getting fired, or being the laughingstock of the office.

Go easy on the reply to all.

Reply to all only when necessary. Remove those on the thread who do not pertain to your response. Most people feel they get enough email as it is. So sending them unwanted mail will only annoy them.

Do not reply to all every single time you receive an email with multiple people on the thread. Replying to all unnecessarily is a great way to irritate the people on the receiving end.

Professionalism is a must.

Be professional in your communications. Use good grammar and choose your words carefully. If writing is not one of your strong points, consider typing it in Microsoft Word first, and then copying and pasting it into an email. Word's spell-check and built-in grammar help will alleviate most embarrassing errors.

Never send poorly written emails. They make you look unprofessional and uneducated and give off the impression that you do not care.

Be prompt with replies.

Always respond within 24 hours or sooner even if you don't have an answer right away. At least let the sender know that you have received their message, and set an expectation for a follow-up.

Never take days, weeks, or months to respond! I recently got a rejection email from a company that I applied to seven years ago. That one made me laugh.

Never hit send when you're ticked off.

Send email when you are in the right frame of mind. Do not send emails when you are mad! Wait awhile until cooler heads prevail before firing off any potentially career-damaging knee-jerk emotional replies. I advocate using the 24-hour rule: Be sure to wait 24 hours before hitting send. Chances are you will want to either edit your message or delete it altogether.

Auto-correct can be a killer.

Be very careful when replying from your mobile. It's easy to make typos when responding from your phone's tiny keyboard.

The auto-correct feature can cause some very strange replies and awkward moments. Always read over your emails from your mobile device at least once.

Get a proofreader on business-affecting emails.

I reached out to Ben Walker, CEO of Transcription Outsourcing in Denver. His company provides transcription services for the legal, medical, and law enforcement professions. Transcription Outsourcing is contractually obligated to have a 99 percent accuracy rate and types thousands of pages per day.

Here is what he had to say about sending clean business communications that are free from embarrassing errors and oversights:

"Have someone in your office read over important emails to clients, especially if your email could have potential legal ramifications pertaining to business agreements. When communicating with your customers, always remember that email is forever and the edit button only works prior to hitting send!"