1. Cybercriminals use HTML tricks to infect computers or deceive individuals into clicking on phishing links.
2. Spammers employ various tricks to bypass anti-spam filters and deliver their marketing messages.
3. HTML support in email clients allows for beautifully-crafted HTML emails from legitimate companies.
4. ZeroFont phishing technique involves using invisible words in emails that are seen by automated spam filters but not by humans.
5. Attackers manipulate email previews in email clients to instill a false sense of legitimacy and security. Vigilance is crucial in dealing with emails.