By appending just a few lines of HTML and CSS ... email contains the "external sender" warning, or on the contrary, touts itself to be "safe," users should be careful prior to opening any links ...

You have to take it back to the basic HTML. We actually ... this extremely helpful link to a blog by David Grenier of Campaign Monitor, " A Guide To CSS Support In Email: 2007 Edition." ...

Cisco Talos says hackers are abusing CSS in emails The stylesheet ... that scan the structure of HTML emails, rather than just their contents. An email security solution could, thus, look for ...