In March 1997, I offered $500 to the first person to publish a verifiable security hole in the latest version of qmail: for example, a way for a user to exploit qmail to take over another account. My offer still stands. Nobody has found any security holes in qmail. [...] In May 2005, Georgi Guninski claimed that some potential 64-bit portability problems allowed a ``remote exploit in qmail-smtpd.'' This claim is denied. Nobody gives gigabytes of memory to each qmail-smtpd process, so there is no problem with qmail's assumption that allocated array lengths fit comfortably into 32 bits.

Erm. Well. I'm not sure what to say. Assuming that array lengths (size_t, IIRC) is a 32-bit type even on 64-bit architectures is wrong. Defending it is insanity.

NP: Layered, Antibreak