Notes about the CEF file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The CEF file type is primarily associated with 'CenturionMail' by CenturionSoft. CenturionMail is a security program for encrypting E-mails as well as files/folders. CenturionMail uses self-decrypting technology so your recipient needs nothing to open the encrypted email except the password.