Debian and Ubuntu use hardened build flags. Such flags are especially relevant for a package like Mailman that uses setgid.
In order to make full use of available hardening features, we need to pass CPPFLAGS and LDFLAGS, but Mailmans Makefile currently not allows that, so we need to patch it. It would be great if attached patch could be applied by Mailman upstream, as it doesn't have a drawback if you're not using the flags.
** Patch added: "patch as used in Debian package" https://bugs.launchpad.net/mailman/+bug/637652/+attachment/2890784/+files/02...