[MereInterest]

In that case, the company domain goes on the whitelist, after being noticed on a weekly glance at the spam folder. The existence of CSS headers isn't a catch-all, but is one more sign that the email is mere marketing, rather than an attempt at human communication.

[sokoloff]

You don't imagine that gmail users will be a prime source of CSS-decorated email within 12 months?

[MereInterest]

I don't imagine that, no. My experience is that gmail addresses are primarily personal email addresses, not mass-marketing emails intended to be a full web page embedded into an email viewer.