Recently, a client reported problems when trying to send mail to certain domains hosted on their own web server. The web server in question was running pd-admin as administration tool set. Mail hosting was done on a separate dedicated mail server. The error message reported by the client was the infamous
550 sorry, user unknown
Checking SMTP through telnet
Having a quick look at the pd-admin (web server) and qmail configuration (mail server) did not reveal any errors in the setup. Thus, a quick telnet check for the email account in question was done to make sure the SMTP service was operating normally:
COMMAND: telnet mx1.company.com 25 RESPONSE: Connected to mx1.company.com. Escape character is ‘^]’. 220 mx1.company.com ESMTP COMMAND: helo hi RESPONSE: 250 mx1.company.com COMMAND: mail from: <your-email@gmail.com> RESPONSE: 250 2.1.0 Ok COMMAND: rcpt to: <user.in.question@company.com> RESPONSE: 550 5.1.1 <user.in.question@company.com>: Recipient address rejected: User unknown in virtual alias table COMMAND: quit RESPONSE: 221 2.0.0 Bye
This check was done on the troubled web server itself. It seemed like that the MX record was pointing to the web server itself and not the mail server.
The solution
When creating customer accounts and setting up domains through pd-admin it automatically creates MX records for these domains too (although the mail server option was not selected during the domain setup on the web server). In case you want to get rid of these MX records
- navigate to Customers
- select Overview and select the Domain option for the customer in question
- then select the MX option
- and finally deactivate the MX record
That should solve it! Yes, a pretty simple solution 😉