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. This happens because email ...

As pageoneresults says in the WebmasterWorld thread: Google has a hard enough time now dealing with html/xhtml. Parsing CSS files and determining whether something is hidden or not is not a solution.

Security researchers are warning about "hidden text salting" in emails Hackers ... Talos outlines how cybercriminals are ...

If you hide text ... hidden text. Cloaking was also used when search engines were identified and showed different content. This was the most sophisticated method. Google downloads CSS and ...