ze-filter  0.8.0
About: ze-filter is a mail filtering software using sendmail milter API and is compatible with mailservers running sendmail or postfix. Hint: Previous project name was "jchkmail".
  Fossies Dox: ze-filter-0.8.0.tgz  ("inofficial" and yet experimental doxygen-generated source code documentation)  

ze-filter : source code documentation

This documentation is just a help for the filter programmer. Maybe I should say : more than just a help...

A little bit of history : this filter beginning was around at the end of year 2001. Most of its development happened during years 2001-2010. So, most of its code were built upon its base, trying to remain coherent.

The first feature of the filter was filtering based on the file extension of attached files (.exe, .com, ...). This was immediately followed by evaluating connection rate of SMTP clients, after a DoS attack against our mail servers. Other filtering ideas were tested and implemented during these 10 years.

So, I can't talk "bottom-up" programming but "incremental" programming. This isn't always a good programming practice, but it's what should be done because, at the beginning, there were no system specifications and I didn't knew what this filter could be.

At the same time, mail filtering is a moving domain, new spam and malware tricks appears all the time.

Within this context, it's not unusual that some incoherence appear in the source code : variable names, code redundancy, ...

Other than the usual goal of documenting this code, this tool is intended to help a task of code revision. And Doxygen is a great tool to do this.