On Thu, 2010-08-05 at 09:44 -0400, Phil Howard wrote: > On Linux, listening to :: in IPv6 has the effect of listening also on > 0.0.0.0 in IPv4, even though only a single socket is involved. Not if you do this (and Dovecot does): opt = 1; setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &opt, sizeof(opt));