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unable to send mails to subdomains - dnslookup defer
Hi,

I am unable to send mail to someone@subdomain.mydomain.com even though there is an exim server running on subdomain.mydomain.com.

I have two exim servers host1.mydomain.com and host2.mydomein.com. the mydomain.com is pointed to host1.mydomain.com. From a mail client hooked to dovecot of host1.mydomain.com, a mail to someuser@host2.mydomain.com fails with error:

May 18 12:39:05 host1 exim[31857]: 2019-05-18 18:09:05 1hRycC-0008Hp-Bg <= someuser@mydomain.com H=([192.168.1.101]) [202.153.45.33] P=esmtpsa X=TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no A=dovecot_plain:someuser S=1483 id=3AFA5894-E4E7-481E-BC5C-AC3CC5AD84C7@mydomain.com
May 18 12:39:05 host1 exim[31859]: 2019-05-18 18:09:05 1hRycC-0008Hp-Bg == someuser@host2.mydomain.comR=dnslookup defer (-1): host lookup did not complete

... Necktwi


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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
On 19/05/2019 14:01, necktwi via Exim-users wrote:
> May 18 12:39:05 host1 exim[31859]: 2019-05-18 18:09:05 1hRycC-0008Hp-Bg == someuser@host2.mydomain.comR=dnslookup defer (-1): host lookup did not complete

It says a DNS lookup isn't working. What do you get when you try one
manually?


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Cheers,
Jeremy

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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
I'm sorry, I didn't get you; what do you mean by manually? I am able to ping host2.mydomain.com from host1.mydomain.com or from any computer on internet. I am able to send/receive mails to/from any mail server on internet from/to host1.mydomain.com. But I am unable to send mail from/to host1.mydomain.com to/from host2.mydomain.com.

... Necktwi

> On 19-May-2019, at 6:55 PM, Jeremy Harris via Exim-users <exim-users@exim.org> wrote:
>
> On 19/05/2019 14:01, necktwi via Exim-users wrote:
>> May 18 12:39:05 host1 exim[31859]: 2019-05-18 18:09:05 1hRycC-0008Hp-Bg == someuser@host2.mydomain.comR=dnslookup defer (-1): host lookup did not complete
>
> It says a DNS lookup isn't working. What do you get when you try one
> manually?
>
>
> --
> Cheers,
> Jeremy
>
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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
I don't need a copy sent direct; I read the mailinglist.
Please use some basic mail etiquette. If Icloud is incapable
of doing that, or makes it hard, you need to consider using
a better provider.

On 19/05/2019 16:15, necktwi via Exim-users wrote:
> I'm sorry, I didn't get you; what do you mean by manually?

I mean, use the "dig" or the "host" utility. Check for all
of MX, A and AAAA lookups.

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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
I just reply all the senders. Now I'm manually sending to the mailing list alone. Is that all you meant by basic mail etiquette? Please let me know. Below are the dig queries you've asked

host1:~ Necktwi$ dig host2.mydomain.com @ns2.zoneedit.com

; <<>> DiG 9.12.3-P4 <<>> host2.mydomain.com @ns2.zoneedit.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29850
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;host2.mydomain.com. IN A

;; ANSWER SECTION:
host2.mydomain.com. 300 IN A 202.153.45.33

;; Query time: 277 msec
;; SERVER: 50.116.49.173#53(50.116.49.173)
;; WHEN: Mon May 20 12:09:27 IST 2019
;; MSG SIZE rcvd: 64
----------------------------------------------------------------------------------------

host1:~ Necktwi$ dig MX host2.mydomain.com @ns2.zoneedit.com

; <<>> DiG 9.12.3-P4 <<>> MX host2.mydomain.com @ns2.zoneedit.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6594
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;host2.mydomain.com. IN MX

;; AUTHORITY SECTION:
mydomain.com. 300 IN SOA dns0.zoneedit.com. zone.zoneedit.com. 1558324701 43200 10800 604800 300

;; Query time: 481 msec
;; SERVER: 50.116.49.173#53(50.116.49.173)
;; WHEN: Mon May 20 12:11:01 IST 2019
;; MSG SIZE rcvd: 103
----------------------------------------------------------------------------------------

host1:/ Necktwi$ dig MX host1.mydomain.com @ns2.zoneedit.com

; <<>> DiG 9.12.3-P4 <<>> MX host1.mydomain.com @ns2.zoneedit.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28404
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;host1.mydomain.com. IN MX

;; AUTHORITY SECTION:
mydomain.com. 165 IN SOA dns0.zoneedit.com. zone.zoneedit.com. 1558324701 43200 10800 604800 300

;; Query time: 459 msec
;; SERVER: 50.116.49.173#53(50.116.49.173)
;; WHEN: Mon May 20 14:21:02 IST 2019
;; MSG SIZE rcvd: 104
----------------------------------------------------------------------------------

host1:/ Necktwi$ dig MX mydomain.com @ns2.zoneedit.com

; <<>> DiG 9.12.3-P4 <<>> MX mydomain.com @ns2.zoneedit.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9824
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;mydomain.com. IN MX

;; ANSWER SECTION:
mydomain.com. 300 IN MX 10 host1.mydomain.com.
mydomain.com. 300 IN MX 10 mydomain.com.
mydomain.com. 300 IN MX 10 mail.mydomain.com.
mydomain.com. 300 IN MX 20 host2.mydomain.com.

;; Query time: 319 msec
;; SERVER: 50.116.49.173#53(50.116.49.173)
;; WHEN: Mon May 20 14:21:13 IST 2019
;; MSG SIZE rcvd: 124
-------------------------------------------------------------------------

I've replaced actual hostnames with pseudo hostnames. I shall provide the exact hostnames if required.

Thank you.

... Necktwi

> On 19-May-2019, at 9:40 PM, Jeremy Harris via Exim-users <exim-users@exim.org> wrote:
>
> I don't need a copy sent direct; I read the mailinglist.
> Please use some basic mail etiquette. If Icloud is incapable
> of doing that, or makes it hard, you need to consider using
> a better provider.
>
> On 19/05/2019 16:15, necktwi via Exim-users wrote:
>> I'm sorry, I didn't get you; what do you mean by manually?
>
> I mean, use the "dig" or the "host" utility. Check for all
> of MX, A and AAAA lookups.
>
> --
> Cheers,
> Jeremy
>
> --
> ## List details at https://lists.exim.org/mailman/listinfo/exim-users
> ## Exim details at http://www.exim.org/
> ## Please use the Wiki with this list - http://wiki.exim.org/


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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
Am 20.05.19 um 11:14 schrieb necktwi via Exim-users:
> I just reply all the senders. Now I'm manually sending to the mailing list alone. Is that all you meant by basic mail etiquette? Please let me know. Below are the dig queries you've asked
>
>
> host1:~ Necktwi$ dig MX host2.mydomain.com @ns2.zoneedit.com
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 4096
> ;; QUESTION SECTION:
> ;host2.mydomain.com. IN MX
>
> ;; AUTHORITY SECTION:
> mydomain.com. 300 IN SOA dns0.zoneedit.com. zone.zoneedit.com. 1558324701 43200 10800 604800 300
>

Did you make your own zone for host2.mydomain.com ? If your Digs are
correct, you did not.

So add host1 and host2 zones to your dns server and you can have mail
delivered to another system,
independent from the main domains emailserver.

"Zone" means: SOA + 2+x NS + MX + A/CNAME for that subdomainname.

best regards,
Marius



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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
necktwi via Exim-users <exim-users@exim.org> (Mo 20 Mai 2019 11:14:36 CEST):
> I just reply all the senders. Now I'm manually sending to the mailing list alone. Is that all you meant by basic mail etiquette? Please let me know. Below are the dig queries you've asked

Yes. (Many(?) Mail User Agents have an action like "list reply" in
contrast to "group reply").

> host1:~ Necktwi$ dig host2.mydomain.com @ns2.zoneedit.com
~~~~~~~~~~~~~~~~~~~

1) is your Exim (the one that is incapable of sending the mails)
running on host1?

2) How can you tell that Exim is using the same name server as you
used with dig?

> host2.mydomain.com. 300 IN A 202.153.45.33

This looks good, MX isn't strictly necessary.

> I've replaced actual hostnames with pseudo hostnames. I shall provide the exact hostnames if required.

It is always a good idea to do as least obfuscation as possible.

--
Heiko
Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
setting mx record to

host2.mydomain.com. 300 IN MX 20 host2.mydomain.com.

instead of

mydomain.com. 300 IN MX 20 host2.mydomain.com.

fixed the issue.

Thank you.

... Necktwi

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Re: unable to send mails to subdomains - dnslookup defer [ In reply to ]
necktwi via Exim-users <exim-users@exim.org> (Di 21 Mai 2019 15:41:43 CEST):
> setting mx record to
> host2.mydomain.com. 300 IN MX 20 host2.mydomain.com.
>
> instead of
> mydomain.com. 300 IN MX 20 host2.mydomain.com.

> fixed the issue.

It is not plausible. If there is no MX for host2.mydomain.com, the dns
lookup router will route the mail to the A record for the destination
"domain" host2.mydomain.com. The MX for the parent domain doesn't hide
the subdomains.

Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann
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