Downloaded to my Mac, ./configure worked fine. But compilation failed with the error
../libmail/libmail_intl.h:49: error: ‘HOST_NAME_MAX’ undeclared here (not in a function)
Looking around, it turns out that HOST_NAME_MAX is not defined on the Mac platform. Instead there is something called _POSIX_HOST_NAME_MAX
Apparently this can be added to the configure process but I regret I don't know enough about that process to do it myself.