GitHub - premailer/premailer: Preflight for HTML email

For the best HTML e-mail delivery results, CSS should be inline. This is a huge pain and a simple newsletter becomes un-managable very quickly. This gem is a solution.CSS styles are converted to inline style attributesChecks style and link[rel=stylesheet] tags and preserves existing inline attributesRelative paths are converted to absolute pathsChecks links in href, src and CSS url('')CSS properties are checked against e-mail client capabilitiesBased on the Email Standards Project's guidesA plain text version is created (optional).