Bad actors have been distributing malware through email for decades. Over time, security technology has evolved and improved greatly, making this task harder for cybercriminals. 20 years ago, we witnessed the frequent distribution of email worms, which caused inboxes to be flooded with them and mail servers to collapse. Although the prevalence of email worms is much lower these days, email phishing is the new prevalent threat users have to face today, despite email being a great tool used by most internet users.
Source:: Avast