1. Phishing Attacks: Malicious attempts to obtain sensitive information by pretending to be a trustworthy entity. 2. Malware: Harmful software that can be spread through email attachments or links. 3. Data Breaches: Unauthorized access to email marketing databases. 4. Spoofing: Creating emails that appear to come from a legitimate source to deceive recipients. 5. Spam: Unsolicited and often irrelevant emails that can harm a brand's reputation.