1. Phishing Attacks: Cybercriminals send emails that appear to be from legitimate sources to steal sensitive information. 2. Malware: Malicious software attached to emails can infect your system and compromise data. 3. Spam: Unsolicited emails that clutter inboxes and can sometimes carry harmful content. 4. Ransomware: Malicious software that encrypts data and demands a ransom for its release.