Package: swaks Version: 20170101.0-2 swaks in the default installation prints this when connection to ipv6 hosts: *** IPv6 not available: requires IO::Socket::INET6. Exiting
after installing libio-socket-inet6-perl, it works. I suggest adding this as a recommends: (or even depends, if one considers IPv6 support essential, what I do, but I don't know what Debian policy says about it) Marian