What is it?
An email scam is as suggested, a scam in a form of an email. It could appear as spam message offering free products, prizes, and very cheap goods, or offering promises of money or other things that can suck you into participating in a scam. However, these emails have a catch and require you to pay a joining fee or to text or call a number.
Responding to a spam message will cause a number of problems. After responding to an email scam, malevolent software may be downloaded onto your computer. It could be spyware, key-loggers, a virus or something even more dangerous. Responding to a spam message could increase the amount of spam message you receive and your credit card details or personal details may have been taken. This could lead to identity theft. You could also pay for something that never comes which results in money being lost.
How do I tell what it is?
An email scam can appear like this:

This email appears as an email scam with a provided link from Twitter. This email is a scam as the email is unable to provide picture within the email. Also, the twitter logo is not present within this email. Twitter does not send these type of emails therefore this email is a scam.
There are many ways in which an email scam can appear as. It could appear as an invitation to encourage you to participate in a lottery or an offer from a lottery you did not register for. It could appear as an offer to join a gambling arrangement which guarantees winners. It could appear as a proposition from overseas or locally for goods. It could also be an appeal to pay a bill in which results in one receiving extra 'benefits' from the person.
How do I prevent this?
Although, email scams seem dangerous and inescapable there are ways in which one can prevent such a scam. The number one thing you must do to prevent email scams is to not open emails (spams) you suspect are scams. Instead of opening these emails, delete them immediately. By doing this you can avoid being sucked into a scam.Using your common sense while checking your emails or surfing the net you have more ability to prevent a scam.'If something is too good to be true, it probably is'. By asking yourself this fundamental question you will be able to prevent most scams.
When you receive an email scam never do anything associated with the email such as:
1. Replying to the email (even to unsubscribe)
2.Opening any links or documents
3.Never call or text a number which is provided with in the email
4.Never enter personal, credit card or banking details
5.Do not send money towards the sender of the email.
By doing these things, you will lessen the chance of falling victim to a scam.