Mail Delivery Subsystem - Adress Not Found - [email protected]

Hi there.

I have a freepbx hosted in a cloud service (specifically for freepbx)
I am in the testing face, so it’s not in production. But testing is going well.

I have the system admin pro and setup the email configuration to work with external smtp through Gmail.
I tested the setup through mail [email protected] and it goes through.

I setup a full backup routine every day at midnight to save it to an external ftp, all this works fine.
I setup to send result notification to my email and here is where the problem is and the question to this forum.
At the end of the backup the smtp sends an email to my email reporting results and that is what I programmed and working fine. But it’s also sending a second email that shows en error. The error report is sent to my email stating

(For security reasons lets assume my external ip is and the hosting url is HOSTING.COM) -

Address not found
Your message wasn’t delivered to [email protected] because the domain couldn’t be found. Check for typos or unnecessary spaces and try again.

Then there is also an explanatory note within the email:

The response from the remote server was:
DNS Error: 124251605 DNS type ‘mx’ lookup of responded with code NXDOMAIN Domain name not found:

With this email is also attached the log file where I can see the backup was successfully completed.

My questions are:

  1. Why the system is sending this second email?
  2. Why is giving this error?

I ran a test using the Debug button and here is the result:

Apr 3 08:16:31 45 postfix/pickup[14068]: 9223C2A22CA: uid=499 from=
Apr 3 08:16:31 45 postfix/cleanup[19240]: 9223C2A22CA: message-id=[email protected]
Apr 3 08:16:31 45 postfix/qmgr[2580]: 9223C2A22CA: from=[email protected], size=535, nrcpt=1 (queue active)
Apr 3 08:16:31 45 postfix/smtp[19242]: connect to[4digits:4hexa:4hexa:4hexa:3hexa:2hexa]:587: Network is unreachable
Apr 3 08:16:33 45 postfix/smtp[19242]: 9223C2A22CA: to=[email protected],[IPV4 EXTERNAL IP]:587, delay=2.1, delays=0.03/0.04/0.59/1.4, dsn=2.0.0, status=sent (250 2.0.0 OK 1491221793 f184sm3544481vkc.6 - gsmtp)
Apr 3 08:16:33 45 postfix/qmgr[2580]: 9223C2A22CA: removed

I will appreciate any help.

Can you nslookup the domain name in question?
Can you nslookup the IP itself ?
This is all related to IP/Reverse and DNS values because most hosts wont accept an email without matching reverse.

Hi Voiptek, thanks for getting back. Not to savvy here. I don’t know how to nslookup the domain nor the IP itself. Can you please illuminate me with that? I know how to get to the box via putty and can log in, but need some more help with that.



maybe you can private messages me the email failure and I can provide you the correct nslookup to do and check it myself from my side.

Thank you VoIPTek, I found the solution and it is working fine now.

Best regards,

If it helps anyone, I resolved this by going to the SMTP Email Setup in the System Admin module. I expected that the “origin” and “domain” field must resolve to a real domain so I set

My Origin: sip
My Domain:

Where “” is a domain I control and resolves in a DNS lookup.

EDIT: OH, also the email has to work as well, so using above example, has to be a valid email. (At this point I’m guessing there’s a better way to resolve this)