When you open up an email from a colleague or friend, you should make sure that it sounds like something that this person would send. In many cases, malware sends out automated messages from a person's email account. These types of messages may also contain strange grammar or spelling.
Additionally, the message itself may seem strange. For example, if you get a message from a friend's email account with pictures from a vacation and this person did not go on a vacation, then it could be a message sent by the malware.
If you want to know more about how you can keep your computer secure, then you should consider contacting Jexet Technologies of Chicago.