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Problems sending Mails to 1&1, United Internet, Schlund, etc. (DE) - snwlhostedeu.com

BWCBWC Cybersecurity Overlord ✭✭✭
in Hosted Email Security

Hi guys,

a HES (EU) customer is having trouble sending mails to customers who have their domains running with the probably market leading Providers 1&1 United Internet and their subbrands, like Schlund etc.

All Mails addressed to one of the domains get bounced with smtp;550 Requested action not taken: mailbox unavailable invalid DNS MX or A/AAAA resource record.

This message is confusing, it's either mailbox unavailable or invalid, can't be both, IMHO.

Message to other recipients are going through without trouble, the affected domains were working just find 2 days ago.

Anyone is having this as well and already reported it?

--Michael@BWC

Category: Hosted Email Security
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Answers

  • franzfranz Newbie

    Hi Michael,


    same for me :(

    The issue started yesterday a 4pm. CEST for my customer.

    Details

    Error:   550 5.4.350 Remote server returned invalid or missing DNS MX or A record for recipient domain -> 550 invalid DNS MX or A/AAAA resource record

    Remoteserver:   euprodsharedou.com.snwlhostedeu.com


    Regards,

    Daniel

  • BWCBWC Cybersecurity Overlord ✭✭✭

    Just in case the support "never" heard about the problems, I opened Case #43666998 about the United Domains dilemma, and Case #43667007 about the incorrect configuration of the zone snwlhostedeu.com with a non resolvable NS for sjl0vm-heswd01.colo.sonicwall.com, which might cause problems resolving your own MX or HES connector.

    --Michael@BWC

  • EF999EF999 Newbie ✭

    We´re having the same issue with all our HES customers.

    I guess there´s nothing we can do but wait for the backend team to fix it..(as always with HES).

  • BWCBWC Cybersecurity Overlord ✭✭✭

    We hope for the worst and fear the best, or was it the other way around? 🤪

    --Michael@BWC

  • BWCBWC Cybersecurity Overlord ✭✭✭

    Ticket #43666998 (United Internet comains) got escalated, status.sonicwall.com does not show anything.

    Thank you for contacting Sonicwall support. We have escalated this issue and escalation team is working on it. We will keep you update with further details.

    You can subscribe on status.sonicwall.com to get latest updates.

    Apologize for the inconvenience.

    --Michael@BWC

  • BWCBWC Cybersecurity Overlord ✭✭✭

    The whole thing might be not just limited to United Domains, another delivery to a different provider got bounced with this message:

    5.0.0 (undefined status)
smtp;550 Sender verification problem

    It might be all related to the wrongful configuration of the NS records for snwlhostedeu.com (and snwlhosted.com).

    --Michael@BWC

  • BWCBWC Cybersecurity Overlord ✭✭✭

    Situation seems to be defused, at the end it might be caused by a small DNS misconfiguration at SNWL.

    --Michael@BWC

  • BWCBWC Cybersecurity Overlord ✭✭✭

    I'am confused, did SNWL really revert back to the DNS misconfiguration and everything will start all over again? BTW, same goes again for snwlhosted.com

    @David W any take on that?


    % dig @8.8.8.8 NS snwlhostedeu.com                      

; <<>> DiG 9.10.6 <<>> @8.8.8.8 NS snwlhostedeu.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27006
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;snwlhostedeu.com.       IN   NS

;; ANSWER SECTION:
snwlhostedeu.com.    1268  IN   NS   sjl0vm-heswd01.colo.sonicwall.com.
snwlhostedeu.com.    1268  IN   NS   ns2.snwlhostedeu.com.
snwlhostedeu.com.    1268  IN   NS   ns1.snwlhostedeu.com.

;; Query time: 22 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Apr 17 09:43:52 CEST 2021
;; MSG SIZE rcvd: 125



% dig @8.8.8.8 A sjl0vm-heswd01.colo.sonicwall.com

; <<>> DiG 9.10.6 <<>> @8.8.8.8 A sjl0vm-heswd01.colo.sonicwall.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 15465
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;sjl0vm-heswd01.colo.sonicwall.com. IN A

;; AUTHORITY SECTION:
sonicwall.com.     299   IN   SOA   pdns1.ultradns.net. hostmaster.sonicwall.com. 2017093180 1200 180 604800 300

;; Query time: 33 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Apr 17 09:44:07 CEST 2021
;; MSG SIZE rcvd: 127

    --Michael@BWC

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