These days, most of us spend at least a quarter of every workday responding to or dealing with different emails. And yet, some of us still haven't fully mastered email etiquette, a field that continually grows more challenging, regardless of its perceived simplicity.

In jobs where communication matters more--like public relations or sales--it's important to ensure that you're coming across as completely professional. Check out the top 5 email mistakes that make salespeople appear otherwise, and learn how to combat them.

1. Overly casual greetings

When you write a professional email, especially to people that you know, it's tempting to say things like "Yo" or "Hey" as a greeting. When you're unsure of what exactly to write, however, it's better to err on the side of more formal than not as a salesperson--as the email recipient can always adjust the response to be less formal rather than more.

2. Typos or grammar mistakes

While a couple typos here or there aren't really a big deal--especially if sending the email from a mobile phone--grammar mistakes demonstrate a lack of mastery of the English language, actually undermining your perceived level of intelligence rather than showcasing it. To show your intellectual savvy in communicating with clients, make sure to avoid typos or grammar mistakes.

3. Sending emails before they're ready

Hitting send too early demonstrates carelessness. Simply taking the extra step to ensure that you've written everything you want to before sending--rather than bombarding the client with multiple emails about the same thing--is very important for emphasizing that you're responsible and organized.

4. Disrespecting other cultures

When we communicate electronically, it can be difficult to get across exactly what we're trying to say. Even the most tech-savvy of people can misread messages. Also keep in mind that, when doing business with people from other cultures, some might come off as more cold or reserved than you're accustomed to--so don't take it personally.

5. Joking inappropriately

Even if you mean well, jokes almost never come off the way that you want to electronically. Often, they get misconstrued or even taken offensively, and you might be better off leaving them out altogether.