I've reviewed hundreds of sales emails for readers of my free weekly newsletter and have found that most of them suffer from the same mistakes.  Here are the 7 most common:

1. Showing insincere interest.

Example: "I hope you are well."

The reasoning behind it: By showing concern for the buyer, the seller is attempting to position himself as the buyer's friend.

Why it's a mistake: The buyer knows that the seller doesn't really care and that the statement of concern just a segue into a sales pitch.

2. Stating the absurdly obvious.

Example: "Managers in this day and age are looking to do more with less."

The reasoning behind it: The seller is hoping that the truism will create a point of agreement between the seller and the buyer, thereby establishing the seller's credibility.

Why it's a mistake: Stating a platitude creates the immediate impression that the remainder of the email will be equally boring and predictable.

3. Focusing on your personal desires.

Example: "I'm excited about our new product."

The reasoning behind it: Sellers wrongly believe that expressing an emotion convinces the buyer to feel that same emotion.

Why it's a mistake: In writing, the naming an an emotion is the opposite of communicating it.  Also, nobody cares about your emotions.

4. Using sales-y language.

Example: "What if I could show you how to..."

The reasoning behind it: They're conscious that they're selling and therefore fall into the habit of using language that seems "natural" to selling.

Why it's a mistake: In our culture, people are predisposed to dislike salespeople and resent it when they feel as if somebody is trying to sell something to them.

5. Claiming that you're not selling.

Example: "I am not trying to sell you anything."

Why people write it: Sellers are trying to get around the fact that people don't like it when salespeople try to sell them something.

Why it's a mistake: It's a lie and the buyer knows it's a lie! Why would the buyer want to do business with a liar?