Problem with external MX with domains on the same server.  [SOLVED]

General discussions around KeyHelp.
Post Reply
User avatar
Victor
Posts: 17
Joined: Sun 21. Jun 2020, 20:23

Problem with external MX with domains on the same server.

Post by Victor »

Hello,

I have this scenario and I'm a little baffled at the situation.
I have 2 customers on the same KeyHelp panel, let's call them customer A and customer B, customer A has the entire domain hosted on KeyHelp (website & e-mails) while customer B has only the website hosted on KeyHelp while his MX records are pointing to google MX-es. Both domains are controlled by my DNS servers, and they have valid records in KeyHelp, Costumer A has the MX of the KeyHelp panel server IP, and Customer B has ONLY the MX-es from google in the DNS Zone Editor.
All dig commands used on the KeyHelp bind master server and on the slave DNS servers are returning correct entries (eg: only the google MX-es are shown for Customer B on a dig @localhost customerB.com mx command)

Now here is the problem.

Code: Select all

Jan 13 16:22:00 ares postfix/submission/smtpd[80767]: NOQUEUE: reject: RCPT from localhost[127.0.0.1]: 550 5.1.1 <zzz@customerB.com>: Recipient address rejected: User unknown in virtual mailbox table; from=<xxx@customerA.com> to=<zzz@customerB.com> proto=ESMTP helo=<keyhelp.panel.com>
All other e-mails sent to customer B are properly sent to the correct MX addreses, but I suspect that somehow being both on the same server and only one of the having the MX-es on the same server, KeyHelp get's somehow confused and tries to deliver the mail to the local server instead of the proper MX records, thus, the errors in the mail.log.

Did someone else run into this problem ?
Any possible fixes available ?

Thank you!
Something something, dark side.
User avatar
Alexander
Keyweb AG
Posts: 3814
Joined: Wed 20. Jan 2016, 02:23

Re: Problem with external MX with domains on the same server.  [SOLVED]

Post by Alexander »

Hello,

Explanation of what happens on the server: The mail server keeps a list of all (mail) domains on the KeyHelp server.
Now when you want to send a mail and the mail server detects that a domain is hosted on the same server, it does not perform a DNS lookup for the MX and instead tries to deliver the mail locally. Since there is no mail account set up in KeyHelp, this error message appears.

There is a simple solution to this: Navigate to the domain overview and select the domain whose MX points outward, than click the "Edit" icon. Now uncheck the checkbox "Email domain / The Domain can be used for email addresses.". Click "Save" -> Done
Mit freundlichen Grüßen / Best regards
Alexander Mahr

**************************************************************
Keyweb AG - Die Hosting Marke
Neuwerkstr. 45/46, 99084 Erfurt / Germany
http://www.keyweb.de - http://www.keyhelp.de
**************************************************************
User avatar
Victor
Posts: 17
Joined: Sun 21. Jun 2020, 20:23

Re: Problem with external MX with domains on the same server.

Post by Victor »

Well that was easy! :D
Thank you very much Alexander!
Something something, dark side.
Post Reply