By appending just a few lines of HTML and CSS code, researcher Louis Dion-Marcil showed how an external sender could hide the very warning from an email message.

A new targeted phishing campaign includes the novel obfuscation technique of using Morse code to hide malicious URLs in an email attachment.

While the process is tedious, encrypting your email address in the HTML code frustrates some of the less sophisticated harvesting programs while giving your human visitors easy access to your inbox.