I have installed Roundcube V.0.9.0 on an OSX Server running OSX 10.8.4. Roundcube is the webmail front-end to Postfix/Dovecot. Everything is working perfectly except for one thing. When an email is received which contains an image file attached, the image is replaced with a pink box in the Roundcube interface. The pink box is a gif file, and seems to be a place holder replacing the original image. This behavior is observed in all browsers: Safari, Chrome, and Firefox running under OSX and also by Internet Explorer running under Windows 8. If I bring up the same email in a regular mailer, like OSX Mail, or Thunderbird, the images display correctly the way they were sent.

I have a TZ215 firewall and virus/trojan scanner, as well as additional virus scanning on the server protecting emails/images/attachments, so, having little or no concern for maleware I have set Roundcube's user preferences in Settings ==> Displaying Messages ==> Display Remote Images ==> to Always. That setting should allow Roundcube to properly display whatever image is received, but it doesn't. When I look at the raw email, I see a properly encoded email with mime-encoded attachments.