Malicious software, often referred to as malware, is any software intentionally designed to cause damage to a computer, server, client, or computer network. Malware can take many forms, such as viruses, worms, Trojan horses, ransomware, spyware, adware, and more. In the context of email marketing, malware is typically distributed through phishing emails, malicious attachments, or links that direct recipients to compromised websites.