Formatting
Using full sentences and correct grammar are important in email etiquette. While you are trying to get to the point, incorrect language usage will diminish your point and make you appear unconcerned or uneducated.
Using small or capital letters only, emojis, bold, different colors and many fonts looks immature and may provoke an unintended response. Save bold and capital letters for banners to parties. In an email, it will almost certainly produce a negative, strong reaction in the recipient. Using dear, a closing, signing your name and thanks always work. As an example, let's look at an email from Barb to her colleague John.
An email from Barb to John:
I can't believe how much work is left. You really need to PICK UP THE PACE if we are going to finish!
In this example, there is no greeting, and a demand almost certainly cause a negative reaction.
If Barb rephrased the email and used correct email etiquette, it might accomplish more, like this:
Dear John,
Thank you for your assistance today with the files. It was very appreciated. I hope we can finish the rest tomorrow.
Kind regards,
Barb
It is important to be sincere in your emails. If Barb's intention was to be passive-aggressive and criticize John for not assisting with the files and to show how angry she was, that will also be translated through an email. The written word can be understood in many ways.
Social Rules and Professional Rules
Generally, the social rule for email is that if you wouldn't say it in real life, you wouldn't put it in an email. A good rule of thumb is to think, 'Would I say or do this in real life?' If you wouldn't, do not write it an email.
Unlike personal email (where it may be acceptable to be less formal) when you send professional email, think of it as a real piece of paper with your company's name or logo on it. If you would not write it on that piece of paper, do not write it an email. Being formal, polite and professional, even with trusted colleagues, will show education and professional responsibility. Also, respect and protect privacy and important information. When forwarding an email, always take out irrelevant information or unwanted contact points. CC (or carbon copy) is for important contact points that need to be in the loop. Use BCC (or blind carbon copy) for blanket emails to multiple parties where others will not be able to see to whom you sent the email.
Most of us are inundated with email in the professional setting. Remember to always ask yourself, is it absolutely necessary to send an email? If it is, remember the same common courtesy that you would expect: a timely response. Quickly acknowledging the email is much better than ignoring it for weeks. Never say you did not receive the email. Unless the email comes back as undeliverable, the sender does indeed know you received it. Avoid using RR (return receipt). It appears intrusive and if the sender is watching over your shoulder.
If you do make an email error, take responsibility and apologize, correcting whatever is wrong.
Most importantly, email does not substitute for talking with, picking up the phone or using Skype to contact someone. This may clear up a misunderstanding created by an email, and its also a human contact.