Nullmailer now supports IPv6 and the Debian packages allows IPv6 literals
in debconf by wrapping them in [ ].

However the maintainer scripts don't cope with IPv6 link-local address
literals having a zone index such as [fe80:5054:ff:fef4:ef81%eth1] which
(in this example) gets corrupted to just "1 e".

Nick

Same behavior happens with passwords: scripts strip square brackets from them too, regardless of the smarthost being an IPv6 address or anything else.

Pretty sure the following contraption in the postinst script is responsible:

Unfortunately I am not completely sure what happens here (and what could
possibly removed or fixed).

Jörg

Pretty sure this also affects passwords with special characters.  I'm not sure what problem the postinst script is trying to solve.

Jay <j__n@yahoo.com> writes:

        This is a colon-separated list of remote servers to which to send each
        message. Each entry contains a remote host name or address followed by
        an optional protocol string 'host protocol'. The protocol name defaults
        to smtp, and may be followed by command-line arguments for that module.
        .
        Examples:
        .
          smarthost
          smarthost smtp --port=10025
          mail.example.com smtp --user=foo --pass=bar
          192.168.1.254 qmqp
          [fe80::5054:ff:fef4:ef81] smtp

Into a syntax compatible with /etc/nullmailer/remotes
(see remotes(5)).

I didn't write that sed snippet, but I guess the intent is to stick to
posix tools to minimized dependencies.

I suspect part of the answer is not to use : as an input separator.
Apparently debconf can handle multiline strings directly using
"debconf-escape", so maybe that can replace the broken sed.