The file extension CEF is used to denote so-called compact embedded fonts, ie embedded fonts of the illustrator vector drawing software. CEF is an Adobe special technique that is optimized especially for the presentation of small fonts.
If fonts are used in a svg document, they can either be embedded directly or linked. When linking (linking) fonts, these are paged out in a CEF file, which Illustrator automatically generates when saving a svg document.
These CEF files can be used in other svg files and save space. Note that CEF is not part of the SVG standard and therefore svg files using this technology can not be viewed by any svg viewer. Such svg files can be displayed with the Adobe SVG Viewer, for example.
Most often resolving problems with opening CEF files is very simple. Just install an appropriate program that supports such files. All of the listed programs support CEF files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of CEF files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate CEF files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the CenturionMail applications is not on the list, select "Browse" option in order to manually locate the directory where CenturionMail has been installed.
Sometimes problems with opening CEF files may not lie with the application itself, but can arise due to other causes, such as: