Spent the day trying to port Mailfilter to Windows properly. It was terrible. No Regular Expressions, no Sockets, no nothing. Well, I knew that from the beginning, but also 50% of all glibc calls are not defined in a typical Windows environment. So before you get to look for a nice Regular Expression library and the Socks API you have to find substitutes for about every bloody (even very basic) system call. But: the Mailfilter development branch does compile and start under Cygwin now. A very warm and satisfying feeling indeed.