Are there scenarios where it is (for some reason) required to place the CSS rule inside the style attribute of the HTML tag directly instead of placing the CSS rule inside a selector in the STYLE element in the HEAD of the HTML email template?
(I am asking for the most common CSS selectors, like type, class, ID, descendant combinations)
Follow-up question:
Gmail seems to be the only relevant email service that does not support the STYLE element. Why is that? (What’s the reasoning behind this decision from Google?)
Yes, for example google gmail won’t handle the STYLE element in the HEAD.
Look at this site for email clients and what they can/can’t do regarding css: http://www.campaignmonitor.com/css/