Victor Duchovni:
> On Fri, Mar 19, 2010 at 06:08:12AM -0600, Glenn English wrote:
>
> > It looks to me like the problem has something to do with DNS, not
> > SMTP, right?
>
> Yes.
>
> > And why would Yahoo be doing a CNAME lookup?
>
> Their MTA does that for all destinations, among other lookups.
>
> > (I checked
> > from a remote site -- my domain's MX server's IP is an A, and I don't
> > see anything having to do with CNAMEs in 'host -t MX slsware.com'.)
>
> Your DNS server is a bit odd:
>
> $ dig +trace -t any slsware.com
>
> ...
> slsware.com. 172800 IN NS ns1.richeyrentals.com.
> slsware.com. 172800 IN NS ns1.slsware.com.
> slsware.com. 172800 IN NS server.slsware.com.
> ;; Received 148 bytes from 192.5.6.30#53(A.GTLD-SERVERS.NET) in 46 ms
>
> ;; connection timed out; no servers could be reached
>
> While asking for "cname" or "mx" works... Perhaps their code does a
> "T_ANY" lookup.
If I recall correctly, Yahoo runs a modified qmail, and indeed:
int dns_cname(sa)
stralloc *sa;
{
int r;
int loop;
for (loop = 0;loop < 10;++loop)
{
if (!sa->len) return loop;
if (sa->s[sa->len - 1] == ']') return loop;
if (sa->s[sa->len - 1] == '.') { --sa->len; continue; }
switch(resolve(sa,T_ANY))
{
case DNS_MEM: return DNS_MEM;
case DNS_SOFT: return DNS_SOFT;
case DNS_HARD: return loop;
default:
...
}
}
return DNS_HARD; /* alias loop */
}
Wietse
