Malware sent as an email delivery would require the recipient to open the attached file. The email is crafted in such a way that the recipient becomes curious about opening the attachment. These unsolicited emails that are spread to many addresses are called email spam. They usually contain a subject and a message body that uses social engineering to get the recipient's attention and eventually have them execute the malware. An example of this can be seen in the following screenshot:
Activities that deceive a person or a group of people to do an activity is called social engineering. With poor security awareness, users may fall into this famous proverbial trap: curiosity killed the cat.