[Mimedefang] $RelayAddr and IPv6?

James Ralston qralston+ml.mimedefang at andrew.cmu.edu
Mon Oct 26 17:31:01 EDT 2015

A quick question for those who are using MIMEDefang on dual-stack
IPv4/IPv6 hosts: what does $RelayAddr contain when an IPv6 relay

The MIMEDefang documentation implies that $RelayAddr will only ever be
a dotted-quad IPv4 address:


        The IP address of the sending relay (as a string consisting of
        four dot-separated decimal numbers.)  One potential use of
        $RelayAddr is to limit mailing to certain lists to people
        within your organization.  This variable is available in
        filter_relay, filter_sender and filter_recipient in addition
        to the body filtering functions.

Either the documentation is outdated, or MIMEDefang has very limited
(and arguably, largely useless) IPv6 support.

I'm kind of hoping the latter isn't the case, as we're building new
dual-stack IPv4/IPv6 MX servers, and we'd prefer to be able to accept
IPv6 SMTP traffic on these new MX servers.  But if MIMEDefang doesn't
have full IPv6 support, then we can't realistically accept IPv6.


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