Re: sendmail error, "MX list for mydomain.com points back to server.mydomain.com"

> On May 19, 2023, at 12:43 AM, vagabond <vagabond@blackfoot.net> wrote:
> 
> On 2023-05-18 19:44, Dan Mahoney (Ports) wrote:
>> Do you see it?  It’s subtle.
>> Your system is asking your own 127.0.0.1 DNS for the AAAA for
>> ns.dreamchaser.org (because sendmail attempts ipv6 before it attempts
>> ipv4)
> 
> ok.
> 
>> You forgot a trailing . in your NS records.  Your DNS kicks back that
>> “hey, I don’t know about ns.dreamchaser.org” so it gives you an SOA
>> record. (answer = 0, authority = 1)
>> is doing lookups for ns.dreamchaser.org.dreamchaser.org because of that.
>> Post your zone file?
> 
> Staring hard, but I still don't see it.
> This is a cut down one (removed comments and other hosts)
> which still fails.
> secondary names have been changed.

DNS is public.  Still not sure why you feel the need to do that.

>> Here’s what I think it happening:  (Have a reference here:
>> Your system is looking at its own rdns/fdns, and discovering that its
>> hostname is ns.dreamchaser.org.dreamchaser.org (probably because your
>> primary IP is not present in /etc/hosts).  It attempts to deliver to
>> itself, and finds that mail SHOULD come to it (since your
>> misconfiguration says your MX is ns.dreamchaser.org.dreamchaser.org
>> AND that’s what you resolve to, but ns.dreamchaser.org.dreamchaser.org
>> isn’t in /etc/mail/local-host-names.
> 
> # cat /etc/hosts
> ::1                     localhost.dreamchaser.org.   localhost
> 127.0.0.1       localhost.dreamchaser.org.   localhost
> 66.109.141.57           ns.dreamchaser.org.          ns

trailing dots don’t typically get used in /etc/hosts, but they’re probably harmless here.  I’d remove them.

>> * Put your primary addresses in /etc/hosts — there are numerous
>> documented cases of sendmail ignoring /etc/hosts but it *might* help
>> clue it in to your proper hostname at least.
> 
> see above
> 
>> * Fix your forward and reverse DNS
>> * (and in fact, stop faking it out.  Fix it at your hosting provider.
>> if your hosting provider is taking this long, find another one)

You had complained of bogus entries, and of them being slow, that was what I had meant.  In a perfect world, you should not need to host a zone file for something you’re not authoritative for, like 141.109.66.in-addr.arpa. as you’re presently doing.  It’s a useful workaround, but will break lookups to anything else in that subnet.

Everything in your zone file *looks* right here.  Is your ISP giving you any kind of ipv6 address?

If you type “hostname” you do get your FQDN, right?

-Dan