From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <81c3dbeae5484ab21859acd28a26c725@quanstro.net>
From: erik quanstrom <quanstro@quanstro.net>
Date: Sun, 24 Aug 2008 08:32:11 -0400
To: arisawa@ar.aichi-u.ac.jp, 9fans@9fans.net
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Subject: Re: [9fans] dns failure in smtp
Topicbox-Message-UUID: 0675f5ca-ead4-11e9-9d60-3106f5b1d025

assuming that my mxdial.c is up-to-date (sources is
failing in a wierd way), that's not the full story.
mxdial calls callmx.  callmx has this code

static int
callmx(DS *ds, char *dest, char *domain)
{
	int fd, i, nmx;
	char addr[Maxstring];

	/* get a list of mx entries */
	nmx = mxlookup(ds, domain);
	if(nmx < 0){
		/* dns isn't working, don't just dial */
		return -1;
	}
	if(nmx == 0){
		if(debug)
			fprint(2, "mxlookup returns nothing\n");
		return dial(dest, 0, 0, 0);
	}
[...]

so if there is no mx record, the normal address is dialed.
(in this case the check against a returned address of 127.0.0.1
is skipped.  i would think if this check is necessary for mx
records, it is also necessary for a records.  but i can't
see why plan 9 cares.  if you do have a loopback, it's likely
for venti.)

in any event that's not what's happening.  using upas/spf
(it's on sources & submitted) we see that that two mx records
are found rfcmail.nanosouffle.net and sounine.nanosouffle.net:

; upas/spf -d nanosouffle.net 75.58.233.41
dnsquery(/net, nanosouffle.net, txt) ->
	dom	nanosouffle.net
	txt	v=spf1 mx -all
dnsquery(/net, nanosouffle.net, mx) ->
	dom	nanosouffle.net
	pref	1
	mx	rfcmail.nanosouffle.net
	dom	nanosouffle.net
	pref	10
	mx	sounine.nanosouffle.net
dnsquery(/net, rfcmail.nanosouffle.net, any) ->
	dom	rfcmail.nanosouffle.net
	ip	75.58.233.40
dnsquery(/net, sounine.nanosouffle.net, any) ->
	dom	sounine.nanosouffle.net
	ip	75.58.233.41

i would guess that dns cs may be or have been confused.
to eliminate the possibility of continuing confusion,
have you tried

	telnet /net.alt/tcp!sounine.nanosouffle.net!smtp

- erik