Thomas Bruederli wrote:
I see one of your messages to the list where all the image attachments having Content-Type: application/octet-stream instead of image/jpeg or whatever. This is also the reason why those attachment are not detected as images and thus no thumbnails are displayed and no inline viewing is offered.
Roundcube tries to detect the mimetypes of uploaded attachment files and this again depends on your server's environment and configuration:
First, there is a mapping file in <roundcubedir>/config/mimetypes.php for simple filename extension to mimetype mapping.
Second, check the 'mime_magic' option which should point to a valid mime description file on your server which is used by PHP fileinfo extension (http://www.php.net/manual/en/book.fileinfo.php).
After reading through the docs and some forum entries, it seems best if you set the 'mime_magic' config option in Roundcube to null. This will let the fileinfo extension use its default mimetype config file.
For debugging purposes, check your error logs for messages like this: PHP Warning: finfo_open(): Failed to load magic database ...
That of course assumes that your PHP installation includes the fileinfo module.
And third, Roundcube tries mime_content_type() which again is a function provided by PHP.
And fourth, as the ultimate fallback, the mimetype submitted by your browser when uploading the attachment file is used.
An easy fix is to add entries for image file extensions to your local config/mimetypes.php file. But try to fix the 'mime_magic' path first.
I'd consider this the last option because usually filename extensions are not very reliable and can easily be faked.
~Thomas