Use desktop preferences for opening attachments
Original reporter says:
Sylpheed does not take into account the XDG default application the desktop environment should use for opening files of a specific MIME/Filetype.
. when I tried to open a PDF file, Sylpheed uses gimp to open the file.
Gimp is the first application in the /usr/share/applications/mimeinfo.cache entry defining which application(s) can read/open/associate with pdf files.
$ grep application/pdf /usr/share/applications/mimeinfo.cache
It should use my desktop's default application from Debian Gnome default spec in /usr/share/applications/gnome-mimeapps.list to open PDF files.
$ grep -i pdf /usr/share/applications/gnome-mimeapps.list
This association can be found using the xdg-mime command:
$ xdg-mime query default application/pdf