These are some useful sources and patches. All stuff is GPL !

Program	Description	Download	Size
BGS qmail patch bundle version 0.1c	A collection of patches for qmail 1.03. Mostly related to security. (For example tarpitting, queue DoS defence, POP3 DELE restriction, etc.)	bgs_qmail_bundle_0.1c.patch	17325
BGS qmail patch bundle version 0.1d	A collection of patches for qmail 1.03. Mostly related to security. (For example tarpitting, queue DoS defence, POP3 DELE restriction, etc.)	bgs_qmail_bundle_0.1d.patch	31101
nullproxy version 0.1	A simple pseudo proxy, that will return an 503 error and az error page notifying the user about the cause the real proxy isn't up.	nullproxy-0.1.tbz2	2686
ubridge	A simple userspace bridging program for two interfaces.	ubridge.c	3966