TYPO3 Core

In t3lib_htmlmail, the MIME type for PNG attachments is set to text/html, but they should be image/png. This causes several mail clients to display newsletters in a strange way. It would also be nice if the MIME type for CSS is added.

In extractMediaLinks(), insert:
case "png":

In getExtendedUrl(), insert:
if ($fileInfo["fileext"] == "png") {$res["content_type"] = "image/png";}
if ($fileInfo["fileext"] == "css") {$res["content_type"] = "text/css";}

(issue imported from #M1421)