Couriergrey is a C++ implementation for greylisting for the Courier mail server.
Distribution archive can be downloaded from here.
Public read access to the repository is also available.
Version 0.3.2 (2012-04-10)
Support for gcc 4.7. Better error handling when new threads cannot be created. Update in the database dump output.
Version 0.3.1 (2012-01-26)
Support for expireing old entries in the greylisting database. Please read the README file for information on how this should be set up on your system.